Merge pull request 'secrets-init: SERVICE_TOKEN читаемый для сервера (после #26 падал на старте)' (#28) from fix/service-token-readable into master

Reviewed-on: #28

README.md

@@ -2,7 +2,38 @@
 
 Почтовый сервер на **Spring Boot WebFlux + R2DBC (PostgreSQL) + Angular**: свой SMTP-сервер на Reactor Netty, веб-почта, очередь отправки, DKIM/SPF/DMARC.
 
-Назначение — наши личные цели (v0.2.3, раздел 75 чек-листа Jambotron): тестовый проект на Jambotron, ловушка почты для dev/staging. Для писем пользователям Jambotron (регистрация, сброс пароля) остаётся Resend.
+Назначение — наша настоящая почта **https://mail.jambocheck.com** (prod Jambotron, системная ВМ, адрес `103.109.235.154`) и тестовый проект на Jambotron.
+
+## Забыл пароль — где взять
+
+**Регистрации нет:** ящики создаёт администратор `admin@jambocheck.com` — веб-почта → Настройки → **MAILBOXES**.
+
+**Ловушка у ящика (TRAP):** Настройки → MAILBOXES → кнопка `outbox` у ящика. Всё, что такой ящик отправляет (SMTP или веб) **на чужие адреса**, никому не доставляется: одна копия ложится в его же INBOX. Письма на наши адреса и рассылки (`alerts-staging@`) доставляются как обычно. Для `staging@` — тестовые письма staging-стенда не попадают к живым людям, а алерты staging доходят до команды.
+
+**Папки по `+метке`:** письмо на `bob+prod@jambocheck.com` ложится в ящик `bob@` в папку **prod** (создаётся сама). В имени ящика и рассылки `+` нельзя. Метка не может быть системной папкой (Spam, Trash …) — тогда INBOX.
+
+**Рассылки (LISTS):** Настройки → LISTS. Письмо на адрес рассылки (`alerts-prod@`) → **каждому участнику своя копия** (своё «прочитано») в папку рассылки. Закрытая рассылка (по умолчанию) принимает письма только от вошедших отправителей (Kuma через `monitor@`, Jambotron) — снаружи 550. Адрес рассылки не может совпадать с ящиком.
+
+**Несколько ящиков у одного логина:** слева в меню **MAILBOXES** — свой ящик, общие, в которых ты участник, и подключённые (кнопка ⊕: адрес + пароль того ящика). Клик — переключиться; «×» — убрать из своего меню.
+
+**Общий ящик** (`support@`, `billing@`): Настройки → MAILBOXES → галочка «shared mailbox» при создании, кнопка `group` — кто может его открывать. Своего пароля и входа у него нет; «прочитано» общее (командный ящик); у письма видно **«Answered by …»** — кто ответил из веб-почты. В профиле открытого чужого ящика пароль/имя не меняются.
+
+**В почтовой программе** (Thunderbird, телефон) общий или подключённый ящик — логин `ящик*свой_логин` (например `support@jambocheck.com*jambotronpw@jambocheck.com`) и **свой** пароль; так и для IMAP, и для SMTP (письма уходят от имени общего ящика).
+
+**Служебное API для Jambotron** (`/api/service/**`, заголовок `Authorization: Bearer <SERVICE_TOKEN>`; токен генерирует `secrets-init` в томе секретов — файл `SERVICE_TOKEN`, без токена API выключено): Общие ящики: `PUT /shared/{address}` `{displayName, members[]}` — создать при отсутствии, точный состав участников; выключение аккаунта убирает его и из общих ящиков.
+`PUT /accounts/{email}` `{displayName, active}` — создать (201 + пароль один раз) или изменить; `active:false` — выключить и убрать из всех рассылок · `POST /accounts/{email}/password` — новый пароль один раз · `GET /accounts/{email}` · `GET /lists` · `PUT /lists/{address}` `{folder, description, openToOutside, members[]}` — точный состав · `DELETE /lists/{address}`.
+
+**Администратор:** `admin@jambocheck.com`, пароль `eK-6oj3TMtZgoXVxlvtCWFI6` (начальный, записан 2026-11-07 по решению владельца; сменили — обновить здесь).
+
+Пароли остальных ящиков (`staging@`, `no-reply@`, `monitor@`) — в репозитории Jambotron: `INFRASTRUCTURE/SECRETS.md`, раздел «Почта mail.jambocheck.com».
+
+| Ситуация | Что делать |
+| :--- | :--- |
+| Пароль `admin@` ещё не меняли | файл `/app/data/initial-passwords.txt` **внутри контейнера** `mail` на ВМ почты (в этом репозитории его нет; лежит в томе `data`, передеплой его не стирает). С компьютера: `ssh root@103.109.235.150`, затем `incus exec --project jambotron-prod incust-prod-react-mail-server -- docker exec jambotron-109cf3bb-mail-1 cat /app/data/initial-passwords.txt`. В логе `mail` строка `Mailbox created…` есть **только до первого передеплоя** |
+| Пароль `admin@` сменили и забыли | новый пароль прямо в базе почты, ящик и письма остаются — попросить α/Ω; команда — Jambotron, `INFRASTRUCTURE/test-stands.md`, раздел «Почта mail.jambocheck.com» |
+| Забыт пароль другого ящика (`staging@`, `no-reply@`, `monitor@`, свой) | войти под `admin@` → Настройки → MAILBOXES → ключик у ящика → новый пароль (показывается один раз) и вписать его туда, где ящик настроен |
+
+Всё о prod-почте (порты, DNS, кто через неё шлёт) — Jambotron, `INFRASTRUCTURE/test-stands.md`.
 
 ## Как устроено
 
@@ -13,7 +44,7 @@
 ```
 
 - **Приём (SMTP).** Команды разбираются по строкам (`LineBasedFrameDecoder`): работает и пачка команд в одном пакете, и строка, разорванная на два пакета. Письмо сохраняется или ставится в очередь **до** ответа `250`; если сохранить не удалось — `451`, и отправитель повторит. Работа с базой и DNS идёт не в сетевом потоке.
-- **TLS.** `STARTTLS` на порту SMTP (RFC 3207) и, если задан `SMTPS_PORT`, неявный TLS (RFC 8314, обычно 465); TLS 1.2/1.3. После `STARTTLS` сессия начинается заново (новый `EHLO`), а команды, присланные открытым текстом вместе со `STARTTLS`, не выполняются — соединение закрывается (CVE-2011-0411). `AUTH` предлагается только внутри TLS (или без него при `SMTP_AUTH_WITHOUT_TLS=true`). Сертификат — свой (`MAIL_TLS_CERT` + `MAIL_TLS_KEY`, например Let's Encrypt) или самоподписанный: создаётся один раз в `MAIL_TLS_DIR` и потом переиспользуется.
+- **TLS.** `STARTTLS` на порту SMTP (RFC 3207) и, если задан `SMTPS_PORT`, неявный TLS (RFC 8314, обычно 465); TLS 1.2/1.3. После `STARTTLS` сессия начинается заново (новый `EHLO`), а команды, присланные открытым текстом вместе со `STARTTLS`, не выполняются — соединение закрывается (CVE-2011-0411). `AUTH` предлагается только внутри TLS (или без него при `SMTP_AUTH_WITHOUT_TLS=true`). Сертификат — свой (`MAIL_TLS_CERT` + `MAIL_TLS_KEY`, например Let's Encrypt) или самоподписанный: создаётся один раз в `MAIL_TLS_DIR` и потом переиспользуется. Свой сертификат сервер перечитывает сам, когда файлы меняются (проверка раз в минуту): обновлённый Let's Encrypt подхватывается без перезапуска, недописанный файл не ломает TLS — остаётся прежний сертификат.
 - **Не открытый релей.**
   - Письмо на свой домен принимается от кого угодно.
   - Письмо на чужой домен — только после `AUTH`, иначе `550 5.7.1 Relaying denied`.
@@ -67,12 +98,14 @@ API: `GET /api/config` (без входа), `/api/me`, `/api/me/password`, `/api
 | `MAIL_DOMAINS` | наши домены, через запятую | `localhost` |
 | `MAIL_HOSTNAME` | имя сервера в SMTP | `localhost` |
 | `MAIL_ADMIN_EMAIL`, `MAIL_ADMIN_PASSWORD` | первый ящик на пустой базе; без пароля — случайный (в `MAIL_PASSWORDS_FILE` или один раз в логе) | `admin@<первый домен>` |
+| `MAIL_ADMINS` | кто управляет ящиками (Настройки → Mailboxes: создать, новый пароль, выключить), через запятую | первый ящик (`MAIL_ADMIN_EMAIL` или `admin@<первый домен>`) |
+| `HTTPS_PORT` | веб-клиент и API по HTTPS тем же сертификатом, что SMTP/IMAP (в `docker-compose.public.yml` — 8443 → 443: `https://mail.<домен>`); 0 — только HTTP на `server.port` | 0 |
 | `MAIL_PASSWORDS_FILE` | файл (права 600), куда дописываются случайные пароли созданных ящиков: первого и ловушки | — (в образе `/app/data/initial-passwords.txt`) |
 | `MAIL_REGISTRATION` | открыть регистрацию | `false` |
 | `MAIL_CATCH_ALL` | ящик-ловушка: письма на адреса без своего ящика здесь (и на чужие домены) — сюда, наружу ничего; ящик создаётся при старте | — |
 | `SMTP_PORT` | порт SMTP | `3025` |
 | `MAIL_TLS` | TLS для SMTP: `STARTTLS` и порт `SMTPS_PORT` | `true` |
-| `MAIL_TLS_CERT`, `MAIL_TLS_KEY` | свой сертификат: PEM-цепочка и ключ PKCS#8; без них — самоподписанный | — |
+| `MAIL_TLS_CERT`, `MAIL_TLS_KEY` | свой сертификат: PEM-цепочка и ключ (PKCS#8, `RSA PRIVATE KEY` или `EC PRIVATE KEY`); перечитывается при изменении; без них — самоподписанный | — |
 | `MAIL_TLS_DIR` | где лежит самоподписанный сертификат | `./tls` (в образе `/app/data/tls`) |
 | `SMTPS_PORT` | порт неявного TLS (465); `0` — выключен | `0` |
 | `IMAP_ENABLED`, `IMAP_PORT`, `IMAPS_PORT` | IMAP: включён; порт со STARTTLS; порт неявного TLS (`0` — выключен) | `true`, `3143`, `0` |
@@ -83,6 +116,22 @@ API: `GET /api/config` (без входа), `/api/me`, `/api/me/password`, `/api
 | `DKIM_DOMAIN`, `DKIM_SELECTOR`, `DKIM_KEYS_DIR` | DKIM | `localhost`, `mail`, `./dkim-keys` |
 | `SPF_ENABLED`, `DMARC_ENABLED` | проверки входящих | `true` |
 | `MAIL_CORS_ORIGINS` | другие источники для веб-клиента (только разработка) | — |
+| `LOGIN_GUARD` | защита от перебора паролей (см. ниже) | `true` |
+| `LOGIN_GUARD_MAX_PER_IP`, `LOGIN_GUARD_MAX_PER_ACCOUNT` | неверных паролей за окно до блокировки: с одного IP; на один ящик с любых IP | `10`, `20` |
+| `LOGIN_GUARD_WINDOW`, `LOGIN_GUARD_BLOCK`, `LOGIN_GUARD_MAX_BLOCK` | окно подсчёта; первая блокировка; потолок (каждая следующая блокировка того же IP вдвое дольше) | `15m`, `15m`, `24h` |
+| `LOGIN_GUARD_TRUSTED_IPS` | IP через запятую, которые не блокируются по IP (ящик всё равно считается) | — |
+
+### Защита от перебора паролей
+
+Один счётчик на всё, где проверяется пароль: `AUTH` в SMTP (25/587/465), `LOGIN`/`AUTHENTICATE` в IMAP, вход в веб-почту, смена пароля.
+
+- **По IP:** 10 неверных паролей за 15 минут → IP заблокирован на 15 минут, следующая блокировка — 30 минут, потом час… до суток. Сутки тишины — счёт сначала.
+- **По ящику:** 20 неверных паролей на один ящик с разных IP (распределённый перебор) → ящик закрыт на 15 минут, **кроме** IP, с которых в него уже входили успешно (30 дней) — так перебором нельзя запереть владельца из его же почтовой программы.
+- Пока блокировка — пароль **не проверяется** вовсе: SMTP `421 4.7.0` и обрыв, IMAP `* BYE` + `NO [UNAVAILABLE]`, веб `429` с `Retry-After`. Неверный пароль отвечается через секунду; после 3 неверных в одном соединении SMTP и IMAP его закрывают.
+- «Нет такого ящика» и «неверный пароль» снаружи не отличить, оба считаются.
+- В логе: `login guard: IP … blocked for 15 min after 10 failed logins (block #1)`.
+- `X-Forwarded-For` веб-входа принимается только от прокси в частной сети (Caddy Jambotron приходит через docker/WireGuard); с публичного адреса заголовок отбрасывается — подменой IP лимит не обойти.
+- Счётчики в памяти: перезапуск их сбрасывает.
 
 ## Разработка
 
@@ -130,15 +179,44 @@ gitea.jambotron.com/jambotron_gang/reactive-mail-server:<первые 8 симв
 docker compose -f docker-compose.image.yml up -d
 ```
 
+### Настоящая почта в интернете (75.6)
+
+`docker-compose.public.yml` — приём писем для `MAIL_DOMAINS` и отправка наружу прямо на MX получателей (`OUTBOUND_MODE=mx`, порт 25), с подписью DKIM; регистрация закрыта, ловушки нет. Нужна своя ВМ с публичным адресом (Jambotron 60.8: «Публичный адрес», SMTP «да» — порт 25 по умолчанию закрыт). На этом адресе открыты:
+
+| Порт | Что |
+|---|---|
+| 25 | SMTP: письма от других серверов (STARTTLS) |
+| 587 | submission для почтовых программ (STARTTLS + вход) — тот же SMTP, что 25 |
+| 465 | SMTPS, неявный TLS |
+| 993 | IMAPS, неявный TLS |
+| 80 | только Let's Encrypt (HTTP-01), сервис `acme` |
+
+Сертификат для `MAIL_HOSTNAME` выпускает и продлевает сервис `acme` (lego, ключ EC256, продление за 30 дней, проверка дважды в сутки); хук кладёт пару в том `tls`, сервер перечитывает её сам. `mail` стартует после первого сертификата. Веб-почта (сервис `mail`, порт `8080`) — через Caddy Jambotron под **другим** именем, например `webmail.<домен>`: `MAIL_HOSTNAME` смотрит на публичный адрес ВМ, а не на Caddy.
+
+Переменные: `MAIL_DOMAINS` (например `jambocheck.com`), `MAIL_HOSTNAME` (`mail.jambocheck.com`), `ACME_EMAIL` (по умолчанию `postmaster@<домен>`).
+
+DNS до первого запуска:
+
+| Запись | Значение |
+|---|---|
+| `A mail.<домен>` | публичный адрес ВМ |
+| PTR публичного адреса | `mail.<домен>` (панель хостера, Reverse DNS) |
+| `MX <домен>` | `10 mail.<домен>` |
+| `TXT <домен>` | `v=spf1 ip4:<публичный адрес> -all` |
+| `TXT _dmarc.<домен>` | `v=DMARC1; p=none; rua=mailto:postmaster@<домен>` |
+| `TXT mail._domainkey.<домен>` | из лога `mail` при первом запуске (ключ DKIM лежит в томе `data`) |
+
+Ящик `admin@<домен>` — пароль в логе `mail` при первом запуске и в `/app/data/initial-passwords.txt`.
+
 ## Не сделано
 
-- [ ] Сертификат Let's Encrypt для настоящей почты (75.6): сейчас — свой файл или самоподписанный.
 - [ ] IMAP: проверить с Thunderbird на настоящем адресе; вложенные папки, CONDSTORE/QRESYNC, поиск по `BODY`/`TEXT` без перебора писем.
 - [ ] Пересылка не берёт вложения исходного письма — их надо прикрепить заново.
 - [ ] Встроенные картинки HTML-писем (`cid:`) показываются как вложения, а не внутри письма.
-- [ ] Защита регистрации и входа от перебора (лимит попыток, капча).
+- [x] Защита входа от перебора: SMTP, IMAP, веб (лимит по IP и по ящику, см. «Защита от перебора паролей»).
+- [ ] Защита регистрации от массового заведения ящиков (лимит, капча) — пока регистрация на публичной почте закрыта.
 - [ ] Письмо нескольким получателям: при ошибке на втором первый может получить его дважды (после повтора отправителя).
-- [ ] Своя настоящая почта: отдельная VPS, порт 25, PTR, отдельный домен (чек-лист Jambotron 75.6).
+- [ ] Настоящая почта (75.6): `docker-compose.public.yml` готов, первый запуск — `mail.jambocheck.com` на публичном адресе Horizon; адрес «прогревать» несколько недель, письма пользователям Jambotron пока через Resend (75.5).
 
 ## Лицензия
 

backend/src/main/java/com/mailserver/config/HttpsConfig.java

@@ -0,0 +1,81 @@
+package com.mailserver.config;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnExpression;
+import org.springframework.context.SmartLifecycle;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.http.server.reactive.HttpHandler;
+import org.springframework.http.server.reactive.ReactorHttpHandlerAdapter;
+import reactor.netty.DisposableServer;
+import reactor.netty.http.server.HttpServer;
+
+import java.time.Duration;
+
+/**
+ * The web client and API over HTTPS on the mail host itself (mailserver.https.port, in public compose 8443 →
+ * published 443): https://mail.jambocheck.com opens the web mail, no second name through Jambotron's Caddy.
+ * Same certificate as SMTP/IMAP (Let's Encrypt from the acme service, reloaded when renewed). The plain HTTP port
+ * (8080) stays for a reverse proxy inside the network (staging: domain in Jambotron).
+ */
+@Configuration
+public class HttpsConfig {
+
+    @Bean
+    @ConditionalOnExpression("${mailserver.https.port:0} > 0 and ${mailserver.tls.enabled:true}")
+    public HttpsServer httpsServer(HttpHandler handler, MailServerConfig.SmtpTlsContext tls,
+                                   @Value("${mailserver.smtp.host:0.0.0.0}") String host,
+                                   @Value("${mailserver.https.port}") int port) {
+        return new HttpsServer(handler, tls, host, port);
+    }
+
+    public static class HttpsServer implements SmartLifecycle {
+
+        private static final Logger log = LoggerFactory.getLogger(HttpsServer.class);
+
+        private final HttpHandler handler;
+        private final MailServerConfig.SmtpTlsContext tls;
+        private final String host;
+        private final int port;
+        private volatile DisposableServer server;
+
+        HttpsServer(HttpHandler handler, MailServerConfig.SmtpTlsContext tls, String host, int port) {
+            this.handler = handler;
+            this.tls = tls;
+            this.host = host;
+            this.port = port;
+        }
+
+        @Override
+        public void start() {
+            server = HttpServer.create()
+                    .host(host)
+                    .port(port)
+                    .secure(spec -> spec.sslContext(tls.context()))
+                    // HSTS: Spring Security adds it for HTTPS requests by itself
+                    .handle(new ReactorHttpHandlerAdapter(handler))
+                    .bindNow(Duration.ofSeconds(30));
+            log.info("HTTPS (web client + API) listening on {}:{}", host, server.port());
+        }
+
+        @Override
+        public void stop() {
+            DisposableServer current = server;
+            if (current != null) {
+                current.disposeNow(Duration.ofSeconds(10));
+                server = null;
+            }
+        }
+
+        @Override
+        public boolean isRunning() {
+            return server != null;
+        }
+
+        public int port() {
+            return server == null ? -1 : server.port();
+        }
+    }
+}

backend/src/main/java/com/mailserver/config/ImapConfig.java

@@ -1,5 +1,6 @@
 package com.mailserver.config;
 
+import com.mailserver.security.LoginGuard;
 import com.mailserver.imap.DbImapStore;
 import com.mailserver.imap.ImapServer;
 import com.mailserver.imap.ImapStore;
@@ -26,13 +27,14 @@ public class ImapConfig {
     @Bean
     public ImapStore imapStore(DatabaseClient db, UserRepository users, UserService userService, MailService mailService,
                                MessageRepository messages, AttachmentRepository attachments, MessageSources sources,
-                               @Value("${mailserver.smtp.hostname:localhost}") String hostname) {
+                               @Value("${mailserver.smtp.hostname:localhost}") String hostname,
-        return new DbImapStore(db, users, userService, mailService, messages, attachments, sources, hostname);
+                               com.mailserver.service.MailboxAccess access) {
+        return new DbImapStore(db, users, userService, mailService, messages, attachments, sources, hostname, access);
     }
 
     @Bean(initMethod = "start", destroyMethod = "stop")
     @ConditionalOnProperty(name = "mailserver.imap.enabled", havingValue = "true", matchIfMissing = true)
-    public ImapServer imapServer(ImapStore store, MailServerConfig.SmtpTlsContext tls,
+    public ImapServer imapServer(ImapStore store, MailServerConfig.SmtpTlsContext tls, LoginGuard guard,
                                  @Value("${mailserver.imap.host:0.0.0.0}") String host,
                                  @Value("${mailserver.imap.port:3143}") int port,
                                  @Value("${mailserver.smtp.hostname:localhost}") String hostname,
@@ -41,12 +43,12 @@ public class ImapConfig {
                                  @Value("${mailserver.imap.idle-timeout:30m}") Duration idleTimeout,
                                  @Value("${mailserver.imap.idle-poll:5s}") Duration idlePoll) {
         return new ImapServer(new ImapServer.Settings(host, port, hostname, authWithoutTls, tls.context(), false,
-                (int) maxLiteral.toBytes(), idleTimeout, idlePoll), store);
+                (int) maxLiteral.toBytes(), idleTimeout, idlePoll), store, guard);
     }
 
     @Bean(initMethod = "start", destroyMethod = "stop")
     @ConditionalOnExpression("'${mailserver.imap.enabled:true}' == 'true' and ${mailserver.imaps.port:0} > 0 and ${mailserver.tls.enabled:true}")
-    public ImapServer imapsServer(ImapStore store, MailServerConfig.SmtpTlsContext tls,
+    public ImapServer imapsServer(ImapStore store, MailServerConfig.SmtpTlsContext tls, LoginGuard guard,
                                   @Value("${mailserver.imap.host:0.0.0.0}") String host,
                                   @Value("${mailserver.imaps.port}") int port,
                                   @Value("${mailserver.smtp.hostname:localhost}") String hostname,
@@ -54,6 +56,6 @@ public class ImapConfig {
                                   @Value("${mailserver.imap.idle-timeout:30m}") Duration idleTimeout,
                                   @Value("${mailserver.imap.idle-poll:5s}") Duration idlePoll) {
         return new ImapServer(new ImapServer.Settings(host, port, hostname, false, tls.context(), true,
-                (int) maxLiteral.toBytes(), idleTimeout, idlePoll), store);
+                (int) maxLiteral.toBytes(), idleTimeout, idlePoll), store, guard);
     }
 }

backend/src/main/java/com/mailserver/config/LoginGuardConfig.java

@@ -0,0 +1,74 @@
+package com.mailserver.config;
+
+import com.mailserver.security.LoginGuard;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.http.server.reactive.ServerHttpRequest;
+import org.springframework.web.server.adapter.ForwardedHeaderTransformer;
+
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.time.Duration;
+import java.util.Arrays;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+/** Brute-force protection (one guard for SMTP, IMAP and the web) and whose X-Forwarded-* headers to believe. */
+@Configuration
+public class LoginGuardConfig {
+
+    @Bean
+    public LoginGuard loginGuard(@Value("${mailserver.login-guard.enabled:true}") boolean enabled,
+                                 @Value("${mailserver.login-guard.max-per-ip:10}") int maxPerIp,
+                                 @Value("${mailserver.login-guard.max-per-account:20}") int maxPerAccount,
+                                 @Value("${mailserver.login-guard.window:15m}") Duration window,
+                                 @Value("${mailserver.login-guard.block:15m}") Duration block,
+                                 @Value("${mailserver.login-guard.max-block:24h}") Duration maxBlock,
+                                 @Value("${mailserver.login-guard.known-ip-ttl:30d}") Duration knownIpTtl,
+                                 @Value("${mailserver.login-guard.trusted-ips:}") String trustedIps,
+                                 @Value("${mailserver.login-guard.failure-delay:1s}") Duration failureDelay) {
+        Set<String> trusted = Arrays.stream(trustedIps.split(","))
+                .map(String::trim).filter(s -> !s.isEmpty()).collect(Collectors.toUnmodifiableSet());
+        return new LoginGuard(new LoginGuard.Settings(enabled, maxPerIp, maxPerAccount, window, block, maxBlock,
+                knownIpTtl, trusted, failureDelay));
+    }
+
+    /**
+     * Replaces Boot's transformer (server.forward-headers-strategy=framework): X-Forwarded-* / Forwarded are believed
+     * only from a proxy in a private network (Jambotron's Caddy comes over the docker network / WireGuard). A request
+     * straight from the internet (the VM's public address) has them removed — otherwise anyone could put a new
+     * X-Forwarded-For into every login attempt and never hit the per-IP limit.
+     */
+    @Bean(name = "forwardedHeaderTransformer")
+    public ForwardedHeaderTransformer forwardedHeaderTransformer() {
+        return new TrustedProxyHeaderTransformer();
+    }
+
+    static final class TrustedProxyHeaderTransformer extends ForwardedHeaderTransformer {
+
+        private final ForwardedHeaderTransformer stripOnly = new ForwardedHeaderTransformer();
+
+        TrustedProxyHeaderTransformer() {
+            stripOnly.setRemoveOnly(true);
+        }
+
+        @Override
+        public ServerHttpRequest apply(ServerHttpRequest request) {
+            return privatePeer(request.getRemoteAddress()) ? super.apply(request) : stripOnly.apply(request);
+        }
+    }
+
+    /** Loopback, 10/8, 172.16/12, 192.168/16, link-local, IPv6 fc00::/7. */
+    static boolean privatePeer(InetSocketAddress peer) {
+        if (peer == null || peer.getAddress() == null) {
+            return false;
+        }
+        InetAddress a = peer.getAddress();
+        if (a.isLoopbackAddress() || a.isSiteLocalAddress() || a.isLinkLocalAddress()) {
+            return true;
+        }
+        byte[] b = a.getAddress();
+        return b.length == 16 && (b[0] & 0xfe) == 0xfc;
+    }
+}

backend/src/main/java/com/mailserver/config/MailAdmins.java

@@ -0,0 +1,36 @@
+package com.mailserver.config;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.stereotype.Component;
+
+import java.util.Arrays;
+import java.util.Locale;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+/**
+ * Who manages mailboxes (Settings → Mailboxes): {@code mailserver.admins} (comma separated), by default the first
+ * mailbox — {@code mailserver.admin.email}, or admin@<first domain>. No role in the database: the list lives in
+ * the configuration, so a stolen mailbox can not make itself an administrator.
+ */
+@Component
+public class MailAdmins {
+
+    private final Set<String> admins;
+
+    public MailAdmins(@Value("${mailserver.admins:}") String admins,
+                      @Value("${mailserver.admin.email:}") String firstMailbox,
+                      MailDomains domains) {
+        String list = !admins.isBlank() ? admins
+                : !firstMailbox.isBlank() ? firstMailbox
+                : "admin@" + domains.domains().iterator().next();
+        this.admins = Arrays.stream(list.split(","))
+                .map(a -> a.trim().toLowerCase(Locale.ROOT))
+                .filter(a -> !a.isEmpty())
+                .collect(Collectors.toUnmodifiableSet());
+    }
+
+    public boolean isAdmin(String email) {
+        return email != null && admins.contains(email.toLowerCase(Locale.ROOT));
+    }
+}

backend/src/main/java/com/mailserver/config/MailDomains.java

@@ -44,6 +44,24 @@ public class MailDomains {
         return domains;
     }
 
+    /**
+     * Address without its "+tag": {@code bob+prod@x} → {@code bob@x}. Mailbox and list names never contain "+",
+     * so the part after it is a label chosen by the sender — the folder the message goes to.
+     */
+    public static String baseOf(String address) {
+        String lower = address.toLowerCase(Locale.ROOT);
+        int at = lower.lastIndexOf('@');
+        int plus = lower.indexOf('+');
+        return plus > 0 && plus < at ? lower.substring(0, plus) + lower.substring(at) : lower;
+    }
+
+    /** The "+tag" of an address, or null: {@code bob+prod@x} → {@code prod}. */
+    public static String tagOf(String address) {
+        int at = address.lastIndexOf('@');
+        int plus = address.indexOf('+');
+        return plus > 0 && plus < at - 1 ? address.substring(plus + 1, at) : null;
+    }
+
     public static String domainOf(String address) {
         int at = address == null ? -1 : address.lastIndexOf('@');
         return at < 0 ? "" : address.substring(at + 1).toLowerCase(Locale.ROOT);

backend/src/main/java/com/mailserver/config/MailServerConfig.java

@@ -1,5 +1,6 @@
 package com.mailserver.config;
 
+import com.mailserver.security.LoginGuard;
 import com.mailserver.delivery.SmtpDeliveryClient;
 import com.mailserver.smtp.MailRouter;
 import com.mailserver.smtp.SmtpServer;
@@ -39,7 +40,7 @@ public class MailServerConfig {
 
     @Bean(initMethod = "start", destroyMethod = "stop")
     @ConditionalOnProperty(name = "mailserver.smtp.enabled", havingValue = "true", matchIfMissing = true)
-    public SmtpServer smtpServer(MailRouter router, SmtpTlsContext tls,
+    public SmtpServer smtpServer(MailRouter router, SmtpTlsContext tls, LoginGuard guard,
                                  @Value("${mailserver.smtp.host:0.0.0.0}") String host,
                                  @Value("${mailserver.smtp.port:3025}") int port,
                                  @Value("${mailserver.smtp.hostname:localhost}") String hostname,
@@ -47,20 +48,20 @@ public class MailServerConfig {
                                  @Value("${mailserver.smtp.auth-without-tls:false}") boolean authWithoutTls,
                                  @Value("${mailserver.smtp.idle-timeout:5m}") Duration idleTimeout) {
         return new SmtpServer(new SmtpServer.Settings(host, port, hostname, maxBytes, authWithoutTls, idleTimeout,
-                tls.context(), false), router);
+                tls.context(), false), router, guard);
     }
 
     /** Implicit TLS (RFC 8314, usually port 465) — only when mailserver.smtps.port is set and TLS is on. */
     @Bean(initMethod = "start", destroyMethod = "stop")
     @ConditionalOnExpression("${mailserver.smtps.port:0} > 0 and ${mailserver.tls.enabled:true}")
-    public SmtpServer smtpsServer(MailRouter router, SmtpTlsContext tls,
+    public SmtpServer smtpsServer(MailRouter router, SmtpTlsContext tls, LoginGuard guard,
                                   @Value("${mailserver.smtp.host:0.0.0.0}") String host,
                                   @Value("${mailserver.smtps.port}") int port,
                                   @Value("${mailserver.smtp.hostname:localhost}") String hostname,
                                   @Value("${mailserver.smtp.max-message-bytes:26214400}") long maxBytes,
                                   @Value("${mailserver.smtp.idle-timeout:5m}") Duration idleTimeout) {
         return new SmtpServer(new SmtpServer.Settings(host, port, hostname, maxBytes, false, idleTimeout,
-                tls.context(), true), router);
+                tls.context(), true), router, guard);
     }
 
     /**

backend/src/main/java/com/mailserver/config/SecurityConfig.java

@@ -52,6 +52,8 @@ public class SecurityConfig {
             .cors(cors -> cors.configurationSource(corsConfigurationSource()))
             .authorizeExchange(exchange -> exchange
                 .pathMatchers("/api/login", "/api/register", "/api/config", "/actuator/health").permitAll()
+                // service API for Jambotron: its own token, checked by ServiceController (not a mailbox login)
+                .pathMatchers("/api/service/**").permitAll()
                 .pathMatchers("/api/**", "/actuator/**").authenticated()
                 // the web client (static files, SPA routes)
                 .anyExchange().permitAll()

backend/src/main/java/com/mailserver/controller/AuthenticationController.java

@@ -1,5 +1,6 @@
 package com.mailserver.controller;
 
+import com.mailserver.config.MailAdmins;
 import com.mailserver.config.MailDomains;
 import com.mailserver.domain.User;
 import com.mailserver.dto.LoginRequest;
@@ -10,11 +11,16 @@ import com.mailserver.dto.ProfileUpdateRequest;
 import com.mailserver.dto.RegisterRequest;
 import com.mailserver.service.MailService;
 import com.mailserver.service.UserService;
+import com.mailserver.security.LoginGuard;
 import com.mailserver.util.JwtUtils;
 import jakarta.validation.Valid;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Value;
+import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
+import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.security.core.Authentication;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PostMapping;
@@ -25,6 +31,8 @@ import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.server.ResponseStatusException;
 import reactor.core.publisher.Mono;
 
+import java.net.InetSocketAddress;
+import java.time.Duration;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
@@ -34,6 +42,10 @@ import java.util.Set;
 @RequestMapping("/api")
 public class AuthenticationController {
 
+    private static final Logger log = LoggerFactory.getLogger(AuthenticationController.class);
+    /** Marker for "no such mailbox or wrong password": both look the same from outside. */
+    private static final User NO_USER = new User();
+
     /** Service addresses nobody can register (RFC 2142 and ours). */
     static final Set<String> RESERVED = Set.of("postmaster", "abuse", "mailer-daemon", "hostmaster", "webmaster",
             "root", "admin", "noreply", "no-reply", "security", "support");
@@ -43,9 +55,14 @@ public class AuthenticationController {
     private final JwtUtils jwtUtils;
     private final MailDomains domains;
     private final boolean registrationEnabled;
+    private final LoginGuard guard;
+    private final MailAdmins admins;
 
     public AuthenticationController(UserService userService, MailService mailService, JwtUtils jwtUtils, MailDomains domains,
-                                    @Value("${mailserver.registration.enabled:false}") boolean registrationEnabled) {
+                                    @Value("${mailserver.registration.enabled:false}") boolean registrationEnabled,
+                                    LoginGuard guard, MailAdmins admins) {
+        this.guard = guard;
+        this.admins = admins;
         this.userService = userService;
         this.mailService = mailService;
         this.jwtUtils = jwtUtils;
@@ -60,23 +77,38 @@ public class AuthenticationController {
     }
 
     @PostMapping("/login")
-    public Mono<ResponseEntity<?>> login(@Valid @RequestBody Mono<LoginRequest> requestMono) {
+    public Mono<ResponseEntity<?>> login(@Valid @RequestBody Mono<LoginRequest> requestMono, ServerHttpRequest http) {
-        return requestMono.flatMap(request ->
+        String ip = clientIp(http);
-            userService.findByEmail(request.getEmail().trim().toLowerCase(Locale.ROOT))
+        return requestMono.flatMap(request -> {
-                .switchIfEmpty(Mono.error(new IllegalArgumentException("Invalid credentials")))
+            String email = request.getEmail().trim().toLowerCase(Locale.ROOT);
+            Duration wait = guard.retryAfter(ip, email);
+            if (!wait.isZero()) {
+                log.warn("WEB {}: login as {} refused, blocked for {}", ip, email, LoginGuard.human(wait));
+                return Mono.just(tooMany(wait));
+            }
+            return userService.findByEmail(email)
+                .map(user -> userService.checkPassword(user, request.getPassword()) ? user : NO_USER)
+                .onErrorResume(IllegalArgumentException.class, e -> Mono.just(NO_USER))
+                .defaultIfEmpty(NO_USER)
                 .flatMap(user -> {
+                    if (user == NO_USER) {
+                        guard.failure(ip, email);
+                        log.warn("WEB {}: authentication failed for {}", ip, email);
+                        Mono<ResponseEntity<?>> answer = Mono.just(ResponseEntity.badRequest().body(Map.of("error", "Invalid credentials")));
+                        Duration delay = guard.failureDelay();
+                        return delay.isZero() ? answer : answer.delayElement(delay);
+                    }
+                    guard.success(ip, email);
+                    if (user.isShared()) {
+                        return Mono.just(ResponseEntity.badRequest().body(Map.of("error",
+                                "This is a shared mailbox: log in with your own mailbox and open it there")));
+                    }
                     if (!user.isActive()) {
                         return Mono.just(ResponseEntity.badRequest().body(Map.of("error", "User is deactivated")));
                     }
-                    if (!userService.checkPassword(user, request.getPassword())) {
-                        return Mono.just(ResponseEntity.badRequest().body(Map.of("error", "Invalid credentials")));
-                    }
                     return Mono.just(ResponseEntity.ok(token(user)));
-                })
+                });
-                .onErrorResume(IllegalArgumentException.class, e ->
+        });
-                    Mono.just(ResponseEntity.badRequest().body(Map.of("error", "Invalid credentials")))
-                )
-        );
     }
 
     /** New mailbox in one of our domains; logs in right away (the answer carries the token). */
@@ -110,22 +142,61 @@ public class AuthenticationController {
 
     @PutMapping("/me")
     public Mono<ProfileResponse> updateMe(Mono<Authentication> auth, @Valid @RequestBody Mono<ProfileUpdateRequest> body) {
-        return user(auth).zipWith(body)
+        return own(auth).zipWith(body)
                 .flatMap(pair -> userService.updateDisplayName(pair.getT1(), pair.getT2().displayName()))
                 .flatMap(this::profile);
     }
 
     @PutMapping("/me/password")
-    public Mono<Map<String, String>> changePassword(Mono<Authentication> auth, @Valid @RequestBody Mono<PasswordChangeRequest> body) {
+    public Mono<Map<String, String>> changePassword(Mono<Authentication> auth, @Valid @RequestBody Mono<PasswordChangeRequest> body,
-        return user(auth).zipWith(body)
+                                                    ServerHttpRequest http) {
-                .flatMap(pair -> userService.changePassword(pair.getT1(), pair.getT2().currentPassword(), pair.getT2().newPassword()))
+        String ip = clientIp(http);
+        return own(auth).zipWith(body)
+                .flatMap(pair -> {
+                    User user = pair.getT1();
+                    // Someone with a stolen session must not guess the current password either
+                    Duration wait = guard.retryAfter(ip, user.getEmail());
+                    if (!wait.isZero()) {
+                        return Mono.error(new ResponseStatusException(HttpStatus.TOO_MANY_REQUESTS,
+                                "Too many failed attempts, try again in " + LoginGuard.human(wait)));
+                    }
+                    if (!userService.checkPassword(user, pair.getT2().currentPassword())) {
+                        guard.failure(ip, user.getEmail());
+                    }
+                    return userService.changePassword(user, pair.getT2().currentPassword(), pair.getT2().newPassword());
+                })
                 .thenReturn(Map.of("message", "Password changed"));
     }
 
+    private static ResponseEntity<?> tooMany(Duration wait) {
+        return ResponseEntity.status(HttpStatus.TOO_MANY_REQUESTS)
+                .header(HttpHeaders.RETRY_AFTER, String.valueOf(Math.max(1, (wait.toMillis() + 999) / 1000)))
+                .body(Map.of("error", "Too many failed logins, try again in " + LoginGuard.human(wait)));
+    }
+
+    /** Client address; behind Caddy it comes from X-Forwarded-For (server.forward-headers-strategy=framework). */
+    static String clientIp(ServerHttpRequest http) {
+        InetSocketAddress address = http.getRemoteAddress();
+        if (address == null) {
+            return "unknown";
+        }
+        return address.getAddress() != null ? address.getAddress().getHostAddress() : address.getHostString();
+    }
+
     private Mono<ProfileResponse> profile(User user) {
         return mailService.usedBytes(user.getId())
                 .map(used -> new ProfileResponse(user.getEmail(), user.getDisplayName(), used,
-                        user.getQuotaBytes() == null ? 0 : user.getQuotaBytes(), user.getCreatedAt()));
+                        user.getQuotaBytes() == null ? 0 : user.getQuotaBytes(), user.getCreatedAt(),
+                        admins.isAdmin(user.getEmail())));
+    }
+
+    /** The session's own mailbox — not a shared / attached / administrator-opened one: no profile changes there. */
+    private Mono<User> own(Mono<Authentication> auth) {
+        return auth.switchIfEmpty(Mono.error(new ResponseStatusException(HttpStatus.UNAUTHORIZED)))
+                .flatMap(a -> com.mailserver.security.Actor.opened(a)
+                        ? Mono.error(new ResponseStatusException(HttpStatus.FORBIDDEN,
+                                "This mailbox is opened from " + com.mailserver.security.Actor.login(a) + " — change it in Settings → MAILBOXES"))
+                        : user(Mono.just(a)));
     }
 
     private Mono<User> user(Mono<Authentication> auth) {

backend/src/main/java/com/mailserver/controller/MailController.java

@@ -150,7 +150,8 @@ public class MailController {
     @PostMapping("/send")
     public Mono<MessageResponse> sendMessage(Mono<Authentication> auth, @Valid @RequestBody Mono<SendRequest> requestMono) {
         return auth.zipWith(requestMono)
-                .flatMap(pair -> submissionService.send(pair.getT1().getName(), pair.getT2()));
+                .flatMap(pair -> submissionService.send(pair.getT1().getName(),
+                        com.mailserver.security.Actor.login(pair.getT1()), pair.getT2()));
     }
 
     // --- Drafts ---

backend/src/main/java/com/mailserver/controller/MailboxAdminController.java

@@ -0,0 +1,237 @@
+package com.mailserver.controller;
+
+import com.mailserver.config.MailAdmins;
+import com.mailserver.config.MailDomains;
+import com.mailserver.domain.User;
+import com.mailserver.dto.LoginResponse;
+import com.mailserver.service.MailDirectory;
+import com.mailserver.service.MailLists;
+import com.mailserver.service.MailboxAccess;
+import com.mailserver.service.MailService;
+import com.mailserver.service.UserService;
+import com.mailserver.util.JwtUtils;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.Size;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.http.HttpStatus;
+import org.springframework.security.core.Authentication;
+import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.PutMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.ResponseStatus;
+import org.springframework.web.bind.annotation.RestController;
+import org.springframework.web.server.ResponseStatusException;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+import java.time.Instant;
+import java.util.Comparator;
+import java.util.List;
+
+/**
+ * Mailboxes of this server for its administrators ({@link MailAdmins}): list, create (no-reply@, monitor@,
+ * support@ — registration stays closed), new password, switch off. A generated password is returned once, in the
+ * answer — it is not logged.
+ */
+@RestController
+@RequestMapping("/api/admin/mailboxes")
+public class MailboxAdminController {
+
+    private static final Logger log = LoggerFactory.getLogger(MailboxAdminController.class);
+    private static final int MIN_PASSWORD = MailDirectory.MIN_PASSWORD;
+
+    public record MailboxView(Long id, String email, String displayName, boolean active, boolean admin, boolean trap,
+                              boolean shared, List<String> members, long usedBytes, long quotaBytes, Instant createdAt) {
+    }
+
+    /** @param password empty — the server generates one and returns it once */
+    /** @param shared shared mailbox (support@): no login of its own — members open it; password ignored */
+    public record CreateRequest(@NotBlank @Size(max = 254) String email, @Size(max = 100) String displayName,
+                                @Size(max = 200) String password, Boolean shared) {
+    }
+
+    public record PasswordRequest(@Size(max = 200) String password) {
+    }
+
+    public record ActiveRequest(boolean active) {
+    }
+
+    public record TrapRequest(boolean trap) {
+    }
+
+    /** @param password the generated password, or null when the administrator chose it */
+    public record Created(MailboxView mailbox, String password) {
+    }
+
+    private final UserService users;
+    private final MailService mail;
+    private final MailDomains domains;
+    private final MailAdmins admins;
+    private final JwtUtils jwt;
+    private final MailDirectory directory;
+    private final MailLists lists;
+    private final MailboxAccess access;
+
+    public MailboxAdminController(UserService users, MailService mail, MailDomains domains, MailAdmins admins, JwtUtils jwt,
+                                  MailDirectory directory, MailLists lists, MailboxAccess access) {
+        this.access = access;
+        this.jwt = jwt;
+        this.directory = directory;
+        this.lists = lists;
+        this.users = users;
+        this.mail = mail;
+        this.domains = domains;
+        this.admins = admins;
+    }
+
+    @GetMapping
+    public Flux<MailboxView> list(Mono<Authentication> auth) {
+        return admin(auth).thenMany(users.all())
+                .concatMap(this::view)
+                .sort(Comparator.comparing(MailboxView::email));
+    }
+
+    @PostMapping
+    @ResponseStatus(HttpStatus.CREATED)
+    public Mono<Created> create(Mono<Authentication> auth, @RequestBody Mono<CreateRequest> body) {
+        return admin(auth).then(body).flatMap(request -> {
+            String chosen = request.password() == null ? "" : request.password();
+            if (!chosen.isEmpty() && chosen.length() < MIN_PASSWORD) {
+                return Mono.error(bad("Password: at least " + MIN_PASSWORD + " characters, or leave it empty to generate one"));
+            }
+            boolean shared = Boolean.TRUE.equals(request.shared());
+            String password = chosen.isEmpty() || shared ? randomPassword() : chosen;
+            return directory.createMailbox(request.email(), request.displayName(), password)
+                    .flatMap(user -> shared ? users.setShared(user, true) : Mono.just(user))
+                    .doOnNext(user -> log.info("{} created by administrator: {}", shared ? "Shared mailbox" : "Mailbox", user.getEmail()))
+                    .flatMap(this::view)
+                    .map(view -> new Created(view, chosen.isEmpty() && !shared ? password : null));
+        });
+    }
+
+    /** New password: the given one, or a generated one returned once. */
+    @PostMapping("/{id}/password")
+    public Mono<Created> password(Mono<Authentication> auth, @PathVariable Long id, @RequestBody Mono<PasswordRequest> body) {
+        return admin(auth).then(body.defaultIfEmpty(new PasswordRequest(null))).flatMap(request -> {
+            String chosen = request.password() == null ? "" : request.password();
+            if (!chosen.isEmpty() && chosen.length() < MIN_PASSWORD) {
+                return Mono.error(bad("Password: at least " + MIN_PASSWORD + " characters, or leave it empty to generate one"));
+            }
+            String password = chosen.isEmpty() ? randomPassword() : chosen;
+            return mailbox(id)
+                    .flatMap(user -> users.setPassword(user, password))
+                    .doOnNext(user -> log.info("Password of {} set by administrator", user.getEmail()))
+                    .flatMap(this::view)
+                    .map(view -> new Created(view, chosen.isEmpty() ? password : null));
+        });
+    }
+
+    /**
+     * Administrator opens a mailbox without its password (Settings → MAILBOXES → Open): a session of that mailbox.
+     * Every opening is logged — who opened which mailbox.
+     */
+    @PostMapping("/{id}/open")
+    public Mono<LoginResponse> open(Mono<Authentication> auth, @PathVariable Long id) {
+        return admin(auth).flatMap(me -> mailbox(id).map(user -> {
+            log.warn("Administrator {} opened mailbox {}", me, user.getEmail());
+            LoginResponse response = new LoginResponse();
+            response.setToken(jwt.generateToken(user.getEmail(), me));
+            response.setEmail(user.getEmail());
+            return response;
+        }));
+    }
+
+    /** Switched off: no login (web, SMTP, IMAP); mail to it is still received. */
+    @PutMapping("/{id}/active")
+    public Mono<MailboxView> active(Mono<Authentication> auth, @PathVariable Long id, @RequestBody Mono<ActiveRequest> body) {
+        return admin(auth).flatMap(me -> body.flatMap(request -> mailbox(id).flatMap(user -> {
+            if (!request.active() && user.getEmail().equalsIgnoreCase(me)) {
+                return Mono.error(bad("You can not switch off your own mailbox"));
+            }
+            log.info("Mailbox {} {} by administrator", user.getEmail(), request.active() ? "switched on" : "switched off");
+            return users.setActive(user, request.active());
+        }))).flatMap(this::view);
+    }
+
+    /** Trap: what the mailbox sends is stored in its own INBOX, nothing leaves the server (staging@). */
+    @PutMapping("/{id}/trap")
+    public Mono<MailboxView> trap(Mono<Authentication> auth, @PathVariable Long id, @RequestBody Mono<TrapRequest> body) {
+        return admin(auth).flatMap(me -> body.flatMap(request -> mailbox(id).flatMap(user -> {
+            log.info("Mailbox {} trap {} by administrator {}", user.getEmail(), request.trap() ? "ON" : "OFF", me);
+            return users.setTrap(user, request.trap());
+        }))).flatMap(this::view);
+    }
+
+    public record MembersRequest(List<String> members) {
+    }
+
+    /** Exactly these members may open the mailbox (shared mailbox; for an ordinary one — delegates). */
+    @PutMapping("/{id}/members")
+    public Mono<MailboxView> members(Mono<Authentication> auth, @PathVariable Long id, @RequestBody Mono<MembersRequest> body) {
+        return admin(auth).flatMap(me -> body.flatMap(request -> mailbox(id).flatMap(user ->
+                directory.setMembers(user, request.members())
+                        .doOnSuccess(v -> log.info("Members of {} set by administrator {}: {}", user.getEmail(), me, request.members()))
+                        .then(users.byId(id)))))
+                .flatMap(this::view);
+    }
+
+    // --- Mailing lists (Settings → LISTS) ---
+
+    public record ListRequest(@Size(max = 50) String folder, @Size(max = 255) String description, boolean openToOutside,
+                              List<String> members) {
+    }
+
+    @GetMapping("/lists")
+    public Flux<MailLists.MailList> lists(Mono<Authentication> auth) {
+        return admin(auth).thenMany(lists.all());
+    }
+
+    /** Creates or replaces the list {@code address} (settings + the exact member set). */
+    @PutMapping("/lists/{address}")
+    public Mono<MailLists.MailList> saveList(Mono<Authentication> auth, @PathVariable String address,
+                                             @RequestBody Mono<ListRequest> body) {
+        return admin(auth).flatMap(me -> body.flatMap(request ->
+                directory.saveList(address, request.folder(), request.description(), request.openToOutside(), request.members())
+                        .doOnNext(list -> log.info("List {} saved by administrator {}: {} members", list.address(), me, list.members().size()))));
+    }
+
+    @DeleteMapping("/lists/{address}")
+    @ResponseStatus(HttpStatus.NO_CONTENT)
+    public Mono<Void> deleteList(Mono<Authentication> auth, @PathVariable String address) {
+        return admin(auth).flatMap(me -> lists.delete(address)
+                .flatMap(deleted -> deleted ? Mono.<Void>empty()
+                        : Mono.error(new ResponseStatusException(HttpStatus.NOT_FOUND, "List not found")))
+                .doOnSuccess(v -> log.info("List {} deleted by administrator {}", address, me)));
+    }
+
+    private Mono<String> admin(Mono<Authentication> auth) {
+        return auth.switchIfEmpty(Mono.error(new ResponseStatusException(HttpStatus.UNAUTHORIZED)))
+                .map(Authentication::getName)
+                .filter(admins::isAdmin)
+                .switchIfEmpty(Mono.error(new ResponseStatusException(HttpStatus.FORBIDDEN, "Only for mail administrators")));
+    }
+
+    private Mono<User> mailbox(Long id) {
+        return users.byId(id).switchIfEmpty(Mono.error(new ResponseStatusException(HttpStatus.NOT_FOUND, "Mailbox not found")));
+    }
+
+    private Mono<MailboxView> view(User user) {
+        return mail.usedBytes(user.getId()).defaultIfEmpty(0L).zipWith(access.members(user.getId()).collectList())
+                .map(pair -> new MailboxView(user.getId(), user.getEmail(), user.getDisplayName(), user.isActive(),
+                        admins.isAdmin(user.getEmail()), user.isTrap(), user.isShared(), pair.getT2(), pair.getT1(), user.getQuotaBytes() == null ? 0 : user.getQuotaBytes(),
+                        user.getCreatedAt()));
+    }
+
+    private static ResponseStatusException bad(String message) {
+        return new ResponseStatusException(HttpStatus.BAD_REQUEST, message);
+    }
+
+    static String randomPassword() {
+        return MailDirectory.randomPassword();
+    }
+}

backend/src/main/java/com/mailserver/controller/MailboxesController.java

@@ -0,0 +1,130 @@
+package com.mailserver.controller;
+
+import com.mailserver.domain.User;
+import com.mailserver.dto.LoginResponse;
+import com.mailserver.security.Actor;
+import com.mailserver.security.LoginGuard;
+import com.mailserver.service.MailboxAccess;
+import com.mailserver.service.UserService;
+import com.mailserver.util.JwtUtils;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.Size;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.server.reactive.ServerHttpRequest;
+import org.springframework.security.core.Authentication;
+import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.ResponseStatus;
+import org.springframework.web.bind.annotation.RestController;
+import org.springframework.web.server.ResponseStatusException;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+import java.time.Duration;
+import java.util.Locale;
+
+/**
+ * The mailboxes of the logged-in user (left menu): own, shared ones it is a member of, attached ones.
+ * Always works for the LOGIN behind the session, also when a shared mailbox is open.
+ */
+@RestController
+@RequestMapping("/api/mailboxes")
+public class MailboxesController {
+
+    private static final Logger log = LoggerFactory.getLogger(MailboxesController.class);
+
+    public record AttachRequest(@NotBlank @Size(max = 254) String email, @NotBlank @Size(max = 200) String password) {
+    }
+
+    private final MailboxAccess access;
+    private final UserService users;
+    private final JwtUtils jwt;
+    private final LoginGuard guard;
+
+    public MailboxesController(MailboxAccess access, UserService users, JwtUtils jwt, LoginGuard guard) {
+        this.access = access;
+        this.users = users;
+        this.jwt = jwt;
+        this.guard = guard;
+    }
+
+    @GetMapping
+    public Flux<MailboxAccess.Entry> mine(Mono<Authentication> auth) {
+        return login(auth).flatMapMany(access::mailboxes);
+    }
+
+    /** A session of this mailbox for the login (switch in the left menu). */
+    @PostMapping("/{email}/session")
+    public Mono<LoginResponse> session(Mono<Authentication> auth, @PathVariable String email) {
+        return login(auth).flatMap(me -> mailbox(email).flatMap(target -> access.has(target.getId(), me.getId())
+                .flatMap(allowed -> {
+                    if (!allowed) {
+                        return Mono.error(new ResponseStatusException(HttpStatus.FORBIDDEN, "No access to this mailbox"));
+                    }
+                    LoginResponse response = new LoginResponse();
+                    boolean own = target.getId().equals(me.getId());
+                    response.setToken(own ? jwt.generateToken(me.getEmail()) : jwt.generateToken(target.getEmail(), me.getEmail()));
+                    response.setEmail(target.getEmail());
+                    return Mono.just(response);
+                })));
+    }
+
+    /** Adds another mailbox the user knows the password of. The password is checked like a login (LoginGuard). */
+    @PostMapping("/attach")
+    @ResponseStatus(HttpStatus.CREATED)
+    public Mono<MailboxAccess.Entry> attach(Mono<Authentication> auth, @RequestBody Mono<AttachRequest> body, ServerHttpRequest http) {
+        String ip = AuthenticationController.clientIp(http);
+        return login(auth).zipWith(body).flatMap(pair -> {
+            User me = pair.getT1();
+            String email = pair.getT2().email().trim().toLowerCase(Locale.ROOT);
+            Duration wait = guard.retryAfter(ip, email);
+            if (!wait.isZero()) {
+                return Mono.error(new ResponseStatusException(HttpStatus.TOO_MANY_REQUESTS,
+                        "Too many failed attempts, try again in " + LoginGuard.human(wait)));
+            }
+            return users.findOptional(email)
+                    .filter(target -> target.isActive() && !target.isShared() && users.checkPassword(target, pair.getT2().password()))
+                    .switchIfEmpty(Mono.defer(() -> {
+                        guard.failure(ip, email);
+                        log.warn("WEB {}: {} failed to attach {}", ip, me.getEmail(), email);
+                        return Mono.error(new ResponseStatusException(HttpStatus.BAD_REQUEST, "Wrong address or password"));
+                    }))
+                    .flatMap(target -> {
+                        if (target.getId().equals(me.getId())) {
+                            return Mono.error(new ResponseStatusException(HttpStatus.BAD_REQUEST, "This is your own mailbox"));
+                        }
+                        guard.success(ip, email);
+                        log.info("{} attached mailbox {}", me.getEmail(), email);
+                        return access.grant(target.getId(), me.getId(), MailboxAccess.ATTACHED)
+                                .then(access.unread(target.getId()))
+                                .map(n -> new MailboxAccess.Entry(target.getEmail(), target.getDisplayName(), MailboxAccess.ATTACHED, false, n));
+                    });
+        });
+    }
+
+    /** Removes the mailbox from the user's menu (attached or shared). */
+    @DeleteMapping("/{email}")
+    @ResponseStatus(HttpStatus.NO_CONTENT)
+    public Mono<Void> leave(Mono<Authentication> auth, @PathVariable String email) {
+        return login(auth).flatMap(me -> mailbox(email).flatMap(target -> access.revoke(target.getId(), me.getId())
+                .flatMap(done -> done ? Mono.<Void>empty()
+                        : Mono.error(new ResponseStatusException(HttpStatus.NOT_FOUND, "Not in your mailboxes")))));
+    }
+
+    private Mono<User> login(Mono<Authentication> auth) {
+        return auth.switchIfEmpty(Mono.error(new ResponseStatusException(HttpStatus.UNAUTHORIZED)))
+                .flatMap(a -> users.findOptional(Actor.login(a)))
+                .switchIfEmpty(Mono.error(new ResponseStatusException(HttpStatus.UNAUTHORIZED)));
+    }
+
+    private Mono<User> mailbox(String email) {
+        return users.findOptional(email)
+                .switchIfEmpty(Mono.error(new ResponseStatusException(HttpStatus.NOT_FOUND, "No such mailbox")));
+    }
+}

backend/src/main/java/com/mailserver/controller/ServiceController.java

@@ -0,0 +1,183 @@
+package com.mailserver.controller;
+
+import com.mailserver.domain.User;
+import com.mailserver.service.MailDirectory;
+import com.mailserver.service.MailLists;
+import com.mailserver.service.MailboxAccess;
+import com.mailserver.service.UserService;
+import jakarta.validation.constraints.Size;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.PutMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestHeader;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+import org.springframework.web.server.ResponseStatusException;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.util.List;
+
+/**
+ * Service API for Jambotron (staff mailboxes): token {@code SERVICE_TOKEN} in {@code Authorization: Bearer …}.
+ * Without the token configured the API is off (404). Accounts: create (password returned ONCE), switch on/off,
+ * new password; lists: the exact settings and members, Jambotron is the source of truth for the lists it keeps.
+ */
+@RestController
+@RequestMapping("/api/service")
+public class ServiceController {
+
+    private static final Logger log = LoggerFactory.getLogger(ServiceController.class);
+
+    /** @param displayName null — unchanged (new account: the name before @) */
+    public record AccountRequest(@Size(max = 100) String displayName, Boolean active) {
+    }
+
+    public record AccountView(String email, String displayName, boolean active, List<String> lists) {
+    }
+
+    /** @param password generated, only when the account was just created or got a new password */
+    public record AccountResult(AccountView account, String password) {
+    }
+
+    public record ListRequest(@Size(max = 50) String folder, @Size(max = 255) String description, boolean openToOutside,
+                              List<String> members) {
+    }
+
+    private final byte[] token;
+    private final UserService users;
+    private final MailLists lists;
+    private final MailDirectory directory;
+    private final MailboxAccess access;
+
+    public ServiceController(@Value("${mailserver.service-token:}") String token, UserService users, MailLists lists,
+                             MailDirectory directory, MailboxAccess access) {
+        this.access = access;
+        this.token = token.isBlank() ? null : token.trim().getBytes(StandardCharsets.UTF_8);
+        this.users = users;
+        this.lists = lists;
+        this.directory = directory;
+    }
+
+    @GetMapping("/accounts/{email}")
+    public Mono<AccountView> account(@RequestHeader(value = "Authorization", required = false) String auth,
+                                     @PathVariable String email) {
+        check(auth);
+        return users.findOptional(email)
+                .switchIfEmpty(Mono.error(new ResponseStatusException(HttpStatus.NOT_FOUND, "No such mailbox")))
+                .flatMap(this::view);
+    }
+
+    /** Creates the account (201 + password once) or updates name / on-off (200). Switched off → out of every list. */
+    @PutMapping("/accounts/{email}")
+    public Mono<ResponseEntity<AccountResult>> saveAccount(@RequestHeader(value = "Authorization", required = false) String auth,
+                                                           @PathVariable String email, @RequestBody Mono<AccountRequest> body) {
+        check(auth);
+        String address = directory.address(email);
+        return body.defaultIfEmpty(new AccountRequest(null, null)).flatMap(request -> users.findOptional(address)
+                .flatMap(user -> update(user, request).flatMap(this::view)
+                        .map(view -> ResponseEntity.ok(new AccountResult(view, null))))
+                .switchIfEmpty(Mono.defer(() -> {
+                    String password = MailDirectory.randomPassword();
+                    return directory.createMailbox(address, request.displayName(), password)
+                            .flatMap(user -> Boolean.FALSE.equals(request.active()) ? update(user, request) : Mono.just(user))
+                            .doOnNext(user -> log.info("Mailbox {} created by Jambotron", user.getEmail()))
+                            .flatMap(this::view)
+                            .map(view -> ResponseEntity.status(HttpStatus.CREATED).body(new AccountResult(view, password)));
+                })));
+    }
+
+    /** New generated password, returned once (Jambotron profile → «new mail password»). */
+    @PostMapping("/accounts/{email}/password")
+    public Mono<AccountResult> password(@RequestHeader(value = "Authorization", required = false) String auth,
+                                        @PathVariable String email) {
+        check(auth);
+        String password = MailDirectory.randomPassword();
+        return users.findOptional(email)
+                .switchIfEmpty(Mono.error(new ResponseStatusException(HttpStatus.NOT_FOUND, "No such mailbox")))
+                .flatMap(user -> users.setPassword(user, password))
+                .doOnNext(user -> log.info("Password of {} set by Jambotron", user.getEmail()))
+                .flatMap(this::view)
+                .map(view -> new AccountResult(view, password));
+    }
+
+    @GetMapping("/lists")
+    public Flux<MailLists.MailList> lists(@RequestHeader(value = "Authorization", required = false) String auth) {
+        check(auth);
+        return lists.all();
+    }
+
+    @PutMapping("/lists/{address}")
+    public Mono<MailLists.MailList> saveList(@RequestHeader(value = "Authorization", required = false) String auth,
+                                             @PathVariable String address, @RequestBody Mono<ListRequest> body) {
+        check(auth);
+        return body.flatMap(request -> directory.saveList(address, request.folder(), request.description(),
+                        request.openToOutside(), request.members()))
+                .doOnNext(list -> log.info("List {} saved by Jambotron: {}", list.address(), list.members()));
+    }
+
+    @DeleteMapping("/lists/{address}")
+    public Mono<ResponseEntity<Void>> deleteList(@RequestHeader(value = "Authorization", required = false) String auth,
+                                                 @PathVariable String address) {
+        check(auth);
+        return lists.delete(address).map(deleted -> deleted
+                ? ResponseEntity.noContent().<Void>build() : ResponseEntity.notFound().<Void>build());
+    }
+
+    public record SharedRequest(@Size(max = 100) String displayName, List<String> members) {
+    }
+
+    public record SharedView(String email, String displayName, List<String> members) {
+    }
+
+    /** Shared mailbox (support@, billing@): created when missing, exactly these members. */
+    @PutMapping("/shared/{address}")
+    public Mono<SharedView> saveShared(@RequestHeader(value = "Authorization", required = false) String auth,
+                                       @PathVariable String address, @RequestBody Mono<SharedRequest> body) {
+        check(auth);
+        return body.flatMap(request -> directory.saveShared(address, request.displayName(), request.members()))
+                .flatMap(user -> access.members(user.getId()).collectList()
+                        .map(members -> new SharedView(user.getEmail(), user.getDisplayName(), members)))
+                .doOnNext(view -> log.info("Shared mailbox {} saved by Jambotron: {}", view.email(), view.members()));
+    }
+
+    private Mono<User> update(User user, AccountRequest request) {
+        Mono<User> named = request.displayName() == null || request.displayName().isBlank() ? Mono.just(user)
+                : users.updateDisplayName(user, request.displayName());
+        if (request.active() == null || request.active() == user.isActive()) {
+            return named;
+        }
+        boolean on = request.active();
+        return named.flatMap(u -> users.setActive(u, on))
+                .flatMap(u -> on ? Mono.just(u) : lists.removeEverywhere(u.getId())
+                        .then(access.removeEverywhere(u.getId())).thenReturn(u))
+                .doOnNext(u -> log.info("Mailbox {} {} by Jambotron", u.getEmail(), on ? "switched on" : "switched off"));
+    }
+
+    private Mono<AccountView> view(User user) {
+        return lists.listsOf(user.getId()).collectList()
+                .map(in -> new AccountView(user.getEmail(), user.getDisplayName(), user.isActive(), in));
+    }
+
+    /** 404 when the API is off, 401 for a wrong token (constant-time compare). */
+    private void check(String auth) {
+        if (token == null) {
+            throw new ResponseStatusException(HttpStatus.NOT_FOUND);
+        }
+        byte[] given = auth != null && auth.startsWith("Bearer ")
+                ? auth.substring(7).trim().getBytes(StandardCharsets.UTF_8) : new byte[0];
+        if (!MessageDigest.isEqual(token, given)) {
+            throw new ResponseStatusException(HttpStatus.UNAUTHORIZED);
+        }
+    }
+}

backend/src/main/java/com/mailserver/domain/Message.java

@@ -54,6 +54,13 @@ public class Message {
     @Column("message_id")
     private String messageId;
 
+    /** Who answered it from the web client (V7) — the login, also for a shared mailbox. */
+    @Column("answered_by")
+    private String answeredBy;
+
+    public String getAnsweredBy() { return answeredBy; }
+    public void setAnsweredBy(String answeredBy) { this.answeredBy = answeredBy; }
+
     public Long getId() { return id; }
     public void setId(Long id) { this.id = id; }
 

backend/src/main/java/com/mailserver/domain/User.java

@@ -30,6 +30,14 @@ public class User {
     @Column("is_active")
     private boolean isActive = true;
 
+    /** Trap: what this mailbox sends is stored in its own INBOX, never delivered (V5). */
+    @Column("is_trap")
+    private boolean isTrap = false;
+
+    /** Shared mailbox (V7): no login of its own, members open it. */
+    @Column("is_shared")
+    private boolean isShared = false;
+
     @Column("created_at")
     private Instant createdAt;
 
@@ -54,6 +62,12 @@ public class User {
     public boolean isActive() { return isActive; }
     public void setActive(boolean active) { isActive = active; }
 
+    public boolean isTrap() { return isTrap; }
+    public void setTrap(boolean trap) { isTrap = trap; }
+
+    public boolean isShared() { return isShared; }
+    public void setShared(boolean shared) { isShared = shared; }
+
     public Instant getCreatedAt() { return createdAt; }
     public void setCreatedAt(Instant createdAt) { this.createdAt = createdAt; }
 }

backend/src/main/java/com/mailserver/dto/MessageResponse.java

@@ -20,6 +20,11 @@ public class MessageResponse {
     private Long folderId;
     private boolean hasAttachments;
     private int attachmentCount;
+    /** login that answered it from the web client, or null */
+    private String answeredBy;
+
+    public String getAnsweredBy() { return answeredBy; }
+    public void setAnsweredBy(String answeredBy) { this.answeredBy = answeredBy; }
 
     public Long getId() { return id; }
     public void setId(Long id) { this.id = id; }

backend/src/main/java/com/mailserver/dto/ProfileResponse.java

@@ -2,5 +2,7 @@ package com.mailserver.dto;
 
 import java.time.Instant;
 
-public record ProfileResponse(String email, String displayName, long usedBytes, long quotaBytes, Instant createdAt) {
+/** @param admin may manage mailboxes ({@link com.mailserver.config.MailAdmins}) */
+public record ProfileResponse(String email, String displayName, long usedBytes, long quotaBytes, Instant createdAt,
+                              boolean admin) {
 }

backend/src/main/java/com/mailserver/dto/SendRequest.java

@@ -26,6 +26,12 @@ public class SendRequest {
 
     private Long draftId;
 
+    /** The message this one answers (web client «Reply»): marked answered, by whom. */
+    private Long replyToId;
+
+    public Long getReplyToId() { return replyToId; }
+    public void setReplyToId(Long replyToId) { this.replyToId = replyToId; }
+
     public String getTo() { return to; }
     public void setTo(String to) { this.to = to; }
 

backend/src/main/java/com/mailserver/imap/DbImapStore.java

@@ -8,6 +8,7 @@ import com.mailserver.repository.MessageRepository;
 import com.mailserver.repository.UserRepository;
 import com.mailserver.service.LocalDelivery;
 import com.mailserver.service.MailService;
+import com.mailserver.service.MailboxAccess;
 import com.mailserver.service.MessageSources;
 import com.mailserver.service.UserService;
 import jakarta.mail.Session;
@@ -45,10 +46,12 @@ public class DbImapStore implements ImapStore {
     private final AttachmentRepository attachments;
     private final MessageSources sources;
     private final String hostname;
+    private final MailboxAccess access;
 
     public DbImapStore(DatabaseClient db, UserRepository users, UserService userService, MailService mailService,
                        MessageRepository messages, AttachmentRepository attachments, MessageSources sources,
-                       String hostname) {
+                       String hostname, MailboxAccess access) {
+        this.access = access;
         this.db = db;
         this.users = users;
         this.userService = userService;
@@ -61,11 +64,9 @@ public class DbImapStore implements ImapStore {
 
     @Override
     public Account authenticate(String username, String password) {
-        User user = users.findByEmail(username.trim().toLowerCase(Locale.ROOT)).block();
+        // login or mailbox*login (shared / attached mailbox in a mail program)
-        if (user == null || !user.isActive() || !userService.checkPassword(user, password)) {
+        User user = access.login(username, password);
-            return null;
+        return user == null ? null : new Account(user.getId(), user.getEmail());
-        }
-        return new Account(user.getId(), user.getEmail());
     }
 
     @Override

backend/src/main/java/com/mailserver/imap/ImapServer.java

@@ -1,5 +1,6 @@
 package com.mailserver.imap;
 
+import com.mailserver.security.LoginGuard;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
 import io.netty.channel.ChannelHandlerContext;
@@ -67,11 +68,17 @@ public class ImapServer {
 
     private final Settings settings;
     private final ImapStore store;
+    private final LoginGuard guard;
     private DisposableServer server;
 
     public ImapServer(Settings settings, ImapStore store) {
+        this(settings, store, LoginGuard.disabled());
+    }
+
+    public ImapServer(Settings settings, ImapStore store, LoginGuard guard) {
         this.settings = settings;
         this.store = store;
+        this.guard = guard;
     }
 
     public void start() {
@@ -98,7 +105,7 @@ public class ImapServer {
                     });
                     ImapSession session = new ImapSession(
                             new ImapSession.Settings(settings.hostname(), settings.tls() != null, settings.authWithoutTls()),
-                            store, remoteIp[0], settings.implicitTls());
+                            store, guard, remoteIp[0], settings.implicitTls());
                     @SuppressWarnings("unchecked")
                     Sinks.Empty<Void>[] idleDone = new Sinks.Empty[1];
 
@@ -135,7 +142,9 @@ public class ImapServer {
                                 log.debug("IMAP {}: connection closed: {}", session.remoteIp, e.toString());
                                 return Mono.just(ImapSession.line("* BYE " + e.getMessage()));
                             })
-                            .takeUntil(response -> session.closing);
+                            // after the tagged line of the command that closes (LOGOUT, too many failed logins), not after
+                            // its first untagged "* BYE" — the tagged answer must still reach the client
+                            .takeUntil(response -> session.closing && !untagged(response));
 
                     return Flux.concat(Mono.just(session.greeting()), responses)
                             .concatMap(response -> response == ImapSession.STARTTLS_READY
@@ -164,6 +173,10 @@ public class ImapServer {
         return new String(bytes, StandardCharsets.US_ASCII).trim().toUpperCase(Locale.ROOT).equals("DONE");
     }
 
+    private static boolean untagged(byte[] response) {
+        return response.length > 1 && response[0] == '*' && response[1] == ' ';
+    }
+
     private static Flux<byte[]> blocking(java.util.concurrent.Callable<List<byte[]>> work) {
         return Mono.fromCallable(work).subscribeOn(Schedulers.boundedElastic()).flatMapIterable(list -> list);
     }

backend/src/main/java/com/mailserver/imap/ImapSession.java

@@ -1,5 +1,6 @@
 package com.mailserver.imap;
 
+import com.mailserver.security.LoginGuard;
 import com.mailserver.service.LocalDelivery;
 import jakarta.mail.Session;
 import jakarta.mail.internet.MimeMessage;
@@ -9,6 +10,7 @@ import org.slf4j.LoggerFactory;
 
 import java.io.ByteArrayInputStream;
 import java.nio.charset.StandardCharsets;
+import java.time.Duration;
 import java.time.Instant;
 import java.time.LocalDate;
 import java.time.ZoneOffset;
@@ -39,6 +41,8 @@ final class ImapSession {
     private static final Logger log = LoggerFactory.getLogger(ImapSession.class);
 
     private static final int MAX_BAD_COMMANDS = 30;
+    /** Wrong passwords in one connection before it is closed. */
+    private static final int MAX_AUTH_FAILURES = 3;
     private static final int SOURCE_CACHE = 16;
     private static final DateTimeFormatter INTERNAL_DATE =
             DateTimeFormatter.ofPattern("dd-MMM-yyyy HH:mm:ss Z", Locale.ENGLISH);
@@ -53,6 +57,7 @@ final class ImapSession {
 
     private final Settings settings;
     private final ImapStore store;
+    private final LoginGuard guard;
     final String remoteIp;
 
     boolean tls;
@@ -78,8 +83,13 @@ final class ImapSession {
     volatile String idleTag;
 
     ImapSession(Settings settings, ImapStore store, String remoteIp, boolean tls) {
+        this(settings, store, LoginGuard.disabled(), remoteIp, tls);
+    }
+
+    ImapSession(Settings settings, ImapStore store, LoginGuard guard, String remoteIp, boolean tls) {
         this.settings = settings;
         this.store = store;
+        this.guard = guard;
         this.remoteIp = remoteIp;
         this.tls = tls;
     }
@@ -254,7 +264,7 @@ final class ImapSession {
             out.add(line(tag + " NO [PRIVACYREQUIRED] Use STARTTLS first"));
             return;
         }
-        loggedIn(tag, store.authenticate(user, password), user, out);
+        checkPassword(tag, user, password, out);
     }
 
     private void authenticate(String tag, ImapReader in, List<byte[]> out) {
@@ -292,13 +302,44 @@ final class ImapSession {
             bad(tag, "Bad PLAIN response", out);
             return;
         }
-        loggedIn(tag, store.authenticate(fields[1], fields[2]), fields[1], out);
+        checkPassword(tag, fields[1], fields[2], out);
+    }
+
+    /** Through the login guard: a blocked IP/mailbox gets no answer about the password and the connection closes. */
+    private void checkPassword(String tag, String user, String password, List<byte[]> out) {
+        Duration wait = guard.retryAfter(remoteIp, user);
+        if (!wait.isZero()) {
+            log.warn("IMAP {}: login as {} refused, blocked for {}", remoteIp, user, LoginGuard.human(wait));
+            out.add(line("* BYE Too many failed logins, try again in " + LoginGuard.human(wait)));
+            out.add(line(tag + " NO [UNAVAILABLE] Too many failed logins"));
+            closing = true;
+            return;
+        }
+        ImapStore.Account result = store.authenticate(user, password);
+        if (result == null) {
+            guard.failure(remoteIp, user);
+            pause(guard.failureDelay());
+        } else {
+            guard.success(remoteIp, user);
+        }
+        loggedIn(tag, result, user, out);
+    }
+
+    private static void pause(Duration delay) {
+        if (delay.isZero()) {
+            return;
+        }
+        try {
+            Thread.sleep(delay.toMillis());
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+        }
     }
 
     private void loggedIn(String tag, ImapStore.Account result, String user, List<byte[]> out) {
         if (result == null) {
             log.warn("IMAP {}: authentication failed for {}", remoteIp, user);
-            if (++badCommands > 5) {
+            if (++badCommands >= MAX_AUTH_FAILURES) {
                 out.add(line("* BYE Too many failed logins"));
                 closing = true;
             }

backend/src/main/java/com/mailserver/security/Actor.java

@@ -0,0 +1,23 @@
+package com.mailserver.security;
+
+import org.springframework.security.core.Authentication;
+
+/**
+ * Who is acting: the mailbox the session belongs to ({@link Authentication#getName()}) and the login behind it —
+ * the same for an own session, another one when a member opened a shared mailbox or an administrator opened one.
+ */
+public final class Actor {
+
+    private Actor() {
+    }
+
+    /** The login behind the session. */
+    public static String login(Authentication auth) {
+        return auth.getDetails() instanceof String by && !by.isBlank() ? by : auth.getName();
+    }
+
+    /** The session is another login's view of this mailbox: no password / profile changes from it. */
+    public static boolean opened(Authentication auth) {
+        return !login(auth).equalsIgnoreCase(auth.getName());
+    }
+}

backend/src/main/java/com/mailserver/security/JwtAuthenticationFilter.java

@@ -43,6 +43,8 @@ public class JwtAuthenticationFilter implements WebFilter {
                 UserDetails userDetails = new User(email, "", Collections.emptyList());
                 UsernamePasswordAuthenticationToken authentication =
                         new UsernamePasswordAuthenticationToken(userDetails, null, Collections.emptyList());
+                // the login that opened this mailbox (shared / attached / administrator's OPEN); see Actor
+                authentication.setDetails(jwtUtils.getByFromToken(token));
 
                 return chain.filter(exchange)
                         .contextWrite(ReactiveSecurityContextHolder.withAuthentication(authentication));

backend/src/main/java/com/mailserver/security/LoginGuard.java

@@ -0,0 +1,257 @@
+package com.mailserver.security;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.scheduling.annotation.Scheduled;
+
+import java.time.Clock;
+import java.time.Duration;
+import java.time.Instant;
+import java.util.ArrayDeque;
+import java.util.Deque;
+import java.util.LinkedHashMap;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * Brute-force protection for every place that checks a password: SMTP AUTH, IMAP LOGIN/AUTHENTICATE, web login,
+ * password change. One instance is shared by all of them, so failures on SMTP and IMAP add up.
+ * <ul>
+ *   <li><b>By IP:</b> {@code maxPerIp} failures within {@code window} → the IP is blocked for {@code block};
+ *       each next block of the same IP is twice as long, up to {@code maxBlock}.</li>
+ *   <li><b>By mailbox:</b> {@code maxPerAccount} failures within {@code window} from any IPs (a distributed attack on
+ *       one mailbox) → the mailbox is blocked for {@code block} — but not for IPs that logged in to it successfully
+ *       before ({@code knownIpTtl}), so an attacker cannot lock the owner's own mail program out.</li>
+ * </ul>
+ * While blocked the password is not checked at all (no answer to a guess) and the caller gets {@link #retryAfter}.
+ * State is in memory: a restart forgets it, which is fine for minutes-long blocks.
+ */
+public class LoginGuard {
+
+    private static final Logger log = LoggerFactory.getLogger(LoginGuard.class);
+
+    /** Upper bound of tracked keys of each kind, so a flood of random usernames/IPs cannot eat the memory. */
+    static final int MAX_KEYS = 100_000;
+    private static final int MAX_KNOWN_IPS_PER_ACCOUNT = 20;
+
+    public record Settings(boolean enabled, int maxPerIp, int maxPerAccount, Duration window, Duration block,
+                           Duration maxBlock, Duration knownIpTtl, Set<String> trustedIps, Duration failureDelay) {
+
+        public static Settings defaults() {
+            return new Settings(true, 10, 20, Duration.ofMinutes(15), Duration.ofMinutes(15), Duration.ofHours(24),
+                    Duration.ofDays(30), Set.of(), Duration.ofSeconds(1));
+        }
+    }
+
+    /** Failures in the window, current block and how many times the key was blocked in a row. */
+    private static final class Counter {
+        final Deque<Instant> failures = new ArrayDeque<>();
+        volatile Instant blockedUntil = Instant.EPOCH;
+        int strikes;
+        Instant lastSeen = Instant.EPOCH;
+    }
+
+    private final Settings settings;
+    private final Clock clock;
+    private final Map<String, Counter> byIp = new ConcurrentHashMap<>();
+    private final Map<String, Counter> byAccount = new ConcurrentHashMap<>();
+    /** account → IPs that logged in to it successfully, with the time of the last success. */
+    private final Map<String, Map<String, Instant>> knownIps = new ConcurrentHashMap<>();
+
+    public LoginGuard(Settings settings) {
+        this(settings, Clock.systemUTC());
+    }
+
+    LoginGuard(Settings settings, Clock clock) {
+        this.settings = settings;
+        this.clock = clock;
+    }
+
+    /** Guard that never blocks (tests, closed networks). */
+    public static LoginGuard disabled() {
+        Settings d = Settings.defaults();
+        return new LoginGuard(new Settings(false, d.maxPerIp(), d.maxPerAccount(), d.window(), d.block(), d.maxBlock(),
+                d.knownIpTtl(), Set.of(), Duration.ZERO));
+    }
+
+    /** Pause before answering "wrong password": slows down guessing inside one connection. */
+    public Duration failureDelay() {
+        return settings.enabled() ? settings.failureDelay() : Duration.ZERO;
+    }
+
+    /**
+     * Zero when the attempt may go on and the password may be checked; otherwise how long the caller has to wait.
+     */
+    public Duration retryAfter(String ip, String account) {
+        if (!settings.enabled()) {
+            return Duration.ZERO;
+        }
+        Instant now = clock.instant();
+        Duration wait = Duration.ZERO;
+        if (!trusted(ip)) {
+            wait = remaining(byIp.get(ip), now);
+        }
+        String acc = normalize(account);
+        if (acc != null && !known(acc, ip, now)) {
+            Duration accountWait = remaining(byAccount.get(acc), now);
+            if (accountWait.compareTo(wait) > 0) {
+                wait = accountWait;
+            }
+        }
+        return wait;
+    }
+
+    public boolean blocked(String ip, String account) {
+        return !retryAfter(ip, account).isZero();
+    }
+
+    /** A wrong password (or an unknown mailbox). */
+    public void failure(String ip, String account) {
+        if (!settings.enabled()) {
+            return;
+        }
+        Instant now = clock.instant();
+        if (!trusted(ip)) {
+            count(byIp, ip, settings.maxPerIp(), now, "IP " + ip);
+        }
+        String acc = normalize(account);
+        if (acc != null) {
+            count(byAccount, acc, settings.maxPerAccount(), now, "mailbox " + acc);
+        }
+    }
+
+    /** A right password: the IP becomes known for the mailbox, failures of this IP are forgiven. */
+    public void success(String ip, String account) {
+        if (!settings.enabled()) {
+            return;
+        }
+        Instant now = clock.instant();
+        String acc = normalize(account);
+        if (acc != null) {
+            if (knownIps.size() < MAX_KEYS || knownIps.containsKey(acc)) {
+                knownIps.compute(acc, (k, ips) -> {
+                    Map<String, Instant> map = ips != null ? ips : new LinkedHashMap<>();
+                    synchronized (map) {
+                        map.remove(ip);
+                        map.put(ip, now);
+                        while (map.size() > MAX_KNOWN_IPS_PER_ACCOUNT) {
+                            map.remove(map.keySet().iterator().next());
+                        }
+                    }
+                    return map;
+                });
+            }
+        }
+        byIp.computeIfPresent(ip, (k, c) -> {
+            c.failures.clear();
+            return c.blockedUntil.isAfter(now) ? c : null;
+        });
+    }
+
+    /** Drops what expired; runs every minute. */
+    @Scheduled(fixedDelay = 60_000)
+    public void sweep() {
+        Instant now = clock.instant();
+        Instant idle = now.minus(settings.maxBlock()).minus(settings.window());
+        byIp.entrySet().removeIf(e -> stale(e.getValue(), now, idle));
+        byAccount.entrySet().removeIf(e -> stale(e.getValue(), now, idle));
+        Instant knownSince = now.minus(settings.knownIpTtl());
+        knownIps.entrySet().removeIf(e -> {
+            synchronized (e.getValue()) {
+                e.getValue().values().removeIf(t -> t.isBefore(knownSince));
+                return e.getValue().isEmpty();
+            }
+        });
+    }
+
+    int trackedIps() {
+        return byIp.size();
+    }
+
+    int trackedAccounts() {
+        return byAccount.size();
+    }
+
+    // ---------------------------------------------------------------------------------------------
+
+    private void count(Map<String, Counter> map, String key, int max, Instant now, String what) {
+        if (map.size() >= MAX_KEYS && !map.containsKey(key)) {
+            sweep();
+            if (map.size() >= MAX_KEYS) {
+                log.warn("login guard: {} keys tracked, {} not counted", map.size(), what);
+                return;
+            }
+        }
+        map.compute(key, (k, existing) -> {
+            Counter c = existing != null ? existing : new Counter();
+            c.lastSeen = now;
+            Instant from = now.minus(settings.window());
+            while (!c.failures.isEmpty() && c.failures.peekFirst().isBefore(from)) {
+                c.failures.pollFirst();
+            }
+            if (c.blockedUntil.isAfter(now)) {
+                return c; // already blocked: attempts are refused before the password check anyway
+            }
+            // A long quiet time after the last block forgives the strikes
+            if (c.strikes > 0 && c.blockedUntil.plus(settings.maxBlock()).isBefore(now)) {
+                c.strikes = 0;
+            }
+            c.failures.addLast(now);
+            if (c.failures.size() >= max) {
+                Duration block = settings.block().multipliedBy(1L << Math.min(c.strikes, 20));
+                if (block.compareTo(settings.maxBlock()) > 0) {
+                    block = settings.maxBlock();
+                }
+                c.strikes++;
+                c.blockedUntil = now.plus(block);
+                c.failures.clear();
+                log.warn("login guard: {} blocked for {} after {} failed logins (block #{})",
+                        what, human(block), max, c.strikes);
+            }
+            return c;
+        });
+    }
+
+    private static Duration remaining(Counter c, Instant now) {
+        if (c == null) {
+            return Duration.ZERO;
+        }
+        Instant until = c.blockedUntil;
+        return until.isAfter(now) ? Duration.between(now, until) : Duration.ZERO;
+    }
+
+    private boolean known(String account, String ip, Instant now) {
+        Map<String, Instant> ips = knownIps.get(account);
+        if (ips == null) {
+            return false;
+        }
+        synchronized (ips) {
+            Instant at = ips.get(ip);
+            return at != null && at.plus(settings.knownIpTtl()).isAfter(now);
+        }
+    }
+
+    private boolean trusted(String ip) {
+        return settings.trustedIps().contains(ip);
+    }
+
+    private static boolean stale(Counter c, Instant now, Instant idle) {
+        return !c.blockedUntil.isAfter(now) && c.lastSeen.isBefore(idle);
+    }
+
+    private static String normalize(String account) {
+        if (account == null) {
+            return null;
+        }
+        String acc = account.trim().toLowerCase(Locale.ROOT);
+        return acc.isEmpty() ? null : acc;
+    }
+
+    /** "15 min" / "2 h" for messages to the user. */
+    public static String human(Duration d) {
+        long minutes = Math.max(1, (d.toSeconds() + 59) / 60);
+        return minutes < 120 ? minutes + " min" : (minutes + 59) / 60 + " h";
+    }
+}

backend/src/main/java/com/mailserver/service/LocalDelivery.java

@@ -54,6 +54,12 @@ public class LocalDelivery implements DeliveryWorker.BounceSender {
     /** Blocking: call from a worker thread. */
     public void deliver(byte[] raw, String mailbox, String remoteIp, String envelopeFrom, boolean trusted)
             throws MessagingException, IOException {
+        deliver(raw, mailbox, null, remoteIp, envelopeFrom, trusted);
+    }
+
+    /** @param folder own folder of the mailbox ("+tag", mailing list), created when missing; null — INBOX */
+    public void deliver(byte[] raw, String mailbox, String folder, String remoteIp, String envelopeFrom, boolean trusted)
+            throws MessagingException, IOException {
         MimeMessage mime = new MimeMessage(Session.getInstance(new Properties()), new ByteArrayInputStream(raw));
 
         String senderEmail = envelopeFrom;
@@ -80,7 +86,7 @@ public class LocalDelivery implements DeliveryWorker.BounceSender {
         com.mailserver.domain.Message stored =
                 mailService.receiveMessage(senderEmail, senderName, mailbox, subject, body.text(), body.html(), spam,
                         addresses(mime, jakarta.mail.Message.RecipientType.TO),
-                        addresses(mime, jakarta.mail.Message.RecipientType.CC)).block();
+                        addresses(mime, jakarta.mail.Message.RecipientType.CC), folder).block();
         if (stored != null) {
             for (FilePart file : attachments(mime)) {
                 mailService.storeIncomingAttachment(stored.getId(), file.name(), file.contentType(), file.bytes());

backend/src/main/java/com/mailserver/service/MailDirectory.java

@@ -0,0 +1,132 @@
+package com.mailserver.service;
+
+import com.mailserver.config.MailDomains;
+import com.mailserver.domain.User;
+import org.springframework.http.HttpStatus;
+import org.springframework.stereotype.Service;
+import org.springframework.web.server.ResponseStatusException;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+import java.security.SecureRandom;
+import java.util.ArrayList;
+import java.util.Base64;
+import java.util.List;
+import java.util.Locale;
+import java.util.regex.Pattern;
+
+/**
+ * Mailboxes and mailing lists share one address space: one rule for both, used by Settings (administrators)
+ * and by the service API (Jambotron). Names never contain "+" — the part after it is a folder label.
+ */
+@Service
+public class MailDirectory {
+
+    private static final Pattern LOCAL_PART = Pattern.compile("[a-z0-9](?:[a-z0-9._-]{0,62}[a-z0-9])?");
+    private static final Pattern FOLDER = Pattern.compile("[A-Za-z0-9][A-Za-z0-9._-]{0,49}");
+    public static final int MIN_PASSWORD = 8;
+
+    private final UserService users;
+    private final MailLists lists;
+    private final MailDomains domains;
+    private final MailboxAccess access;
+
+    public MailDirectory(UserService users, MailLists lists, MailDomains domains, MailboxAccess access) {
+        this.access = access;
+        this.users = users;
+        this.lists = lists;
+        this.domains = domains;
+    }
+
+    /** Lower-case address of our domain with an allowed name, or 400. */
+    public String address(String raw) {
+        String email = raw == null ? "" : raw.trim().toLowerCase(Locale.ROOT);
+        int at = email.lastIndexOf('@');
+        if (at <= 0 || !LOCAL_PART.matcher(email.substring(0, at)).matches()) {
+            throw bad("Not a mailbox address: " + email + " (letters, digits, . _ - ; no +)");
+        }
+        if (!domains.isLocal(email)) {
+            throw bad("Only in " + String.join(", ", domains.domains().stream().sorted().toList()));
+        }
+        return email;
+    }
+
+    /** New mailbox; the address must not be taken by a mailbox or a list. 409 when taken. */
+    public Mono<User> createMailbox(String rawEmail, String displayName, String password) {
+        String email = address(rawEmail);
+        if (password == null || password.length() < MIN_PASSWORD) {
+            return Mono.error(bad("Password: at least " + MIN_PASSWORD + " characters"));
+        }
+        return lists.exists(email).flatMap(isList -> isList
+                ? Mono.<User>error(new ResponseStatusException(HttpStatus.CONFLICT, "This address is a mailing list"))
+                : users.register(email, password, displayName)
+                        .onErrorMap(IllegalArgumentException.class,
+                                e -> new ResponseStatusException(HttpStatus.CONFLICT, "This mailbox already exists")));
+    }
+
+    /**
+     * Creates or replaces a list. Members: mailboxes of this server (addresses); unknown ones → 400 naming them.
+     */
+    public Mono<MailLists.MailList> saveList(String rawAddress, String rawFolder, String description,
+                                             boolean openToOutside, List<String> members) {
+        String address = address(rawAddress);
+        String folder = rawFolder == null || rawFolder.isBlank() ? null : rawFolder.trim();
+        if (folder != null && (!FOLDER.matcher(folder).matches()
+                || MailService.SYSTEM_FOLDERS.stream().anyMatch(folder::equalsIgnoreCase))) {
+            return Mono.error(bad("Folder: letters, digits, . _ - (up to 50), not a system folder; empty — INBOX"));
+        }
+        String about = description == null || description.isBlank() ? null : description.trim();
+        if (about != null && about.length() > 255) {
+            return Mono.error(bad("Description: up to 255 characters"));
+        }
+        List<String> wanted = members == null ? List.of()
+                : members.stream().map(m -> m.trim().toLowerCase(Locale.ROOT)).filter(m -> !m.isEmpty()).distinct().toList();
+        return users.findOptional(address).hasElement().flatMap(isMailbox -> {
+            if (isMailbox) {
+                return Mono.error(new ResponseStatusException(HttpStatus.CONFLICT, "This address is a mailbox"));
+            }
+            List<String> unknown = new ArrayList<>();
+            return Flux.fromIterable(wanted)
+                    .concatMap(member -> users.findOptional(member)
+                            .map(User::getId)
+                            .switchIfEmpty(Mono.fromRunnable(() -> unknown.add(member))))
+                    .collectList()
+                    .flatMap(ids -> unknown.isEmpty()
+                            ? lists.save(address, folder, about, openToOutside, ids)
+                            : Mono.error(bad("No such mailbox: " + String.join(", ", unknown))));
+        });
+    }
+
+    /** Exactly these members (mailboxes of this server) for the mailbox; unknown ones → 400 naming them. */
+    public Mono<Void> setMembers(User mailbox, List<String> members) {
+        List<String> wanted = members == null ? List.of()
+                : members.stream().map(m -> m.trim().toLowerCase(Locale.ROOT)).filter(m -> !m.isEmpty()).distinct().toList();
+        List<String> unknown = new ArrayList<>();
+        return Flux.fromIterable(wanted)
+                .concatMap(member -> users.findOptional(member).map(User::getId)
+                        .switchIfEmpty(Mono.fromRunnable(() -> unknown.add(member))))
+                .collectList()
+                .flatMap(ids -> unknown.isEmpty() ? access.setMembers(mailbox.getId(), ids)
+                        : Mono.error(bad("No such mailbox: " + String.join(", ", unknown))));
+    }
+
+    /** Shared mailbox: created when missing (no login of its own), then exactly these members. */
+    public Mono<User> saveShared(String rawAddress, String displayName, List<String> members) {
+        String address = address(rawAddress);
+        return users.findOptional(address)
+                .switchIfEmpty(Mono.defer(() -> createMailbox(address, displayName, randomPassword())))
+                .flatMap(user -> user.isShared() ? Mono.just(user) : users.setShared(user, true))
+                .flatMap(user -> displayName == null || displayName.isBlank() ? Mono.just(user) : users.updateDisplayName(user, displayName))
+                .flatMap(user -> setMembers(user, members).thenReturn(user));
+    }
+
+    public static String randomPassword() {
+        byte[] bytes = new byte[18];
+        new SecureRandom().nextBytes(bytes);
+        return Base64.getUrlEncoder().withoutPadding().encodeToString(bytes);
+    }
+
+    public static ResponseStatusException bad(String message) {
+        return new ResponseStatusException(HttpStatus.BAD_REQUEST, message);
+    }
+}

backend/src/main/java/com/mailserver/service/MailLists.java

@@ -0,0 +1,101 @@
+package com.mailserver.service;
+
+import org.springframework.r2dbc.core.DatabaseClient;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Locale;
+
+/**
+ * Mailing lists (V6): {@code alerts-prod@} → every member gets their own copy in the list's folder.
+ * Kept by the administrators (Settings → LISTS) and by Jambotron through the service API.
+ */
+@Service
+public class MailLists {
+
+    /** @param folder where members get the copy; null — INBOX */
+    public record MailList(Long id, String address, String folder, String description, boolean openToOutside,
+                           List<String> members) {
+    }
+
+    private final DatabaseClient db;
+
+    public MailLists(DatabaseClient db) {
+        this.db = db;
+    }
+
+    public Mono<MailList> find(String address) {
+        return db.sql("SELECT id, address, folder, description, open_to_outside FROM mail_lists WHERE address = :a")
+                .bind("a", address.toLowerCase(Locale.ROOT))
+                .map((row, meta) -> new MailList(row.get("id", Long.class), row.get("address", String.class),
+                        row.get("folder", String.class), row.get("description", String.class),
+                        Boolean.TRUE.equals(row.get("open_to_outside", Boolean.class)), List.of()))
+                .one()
+                .flatMap(this::withMembers);
+    }
+
+    public Mono<Boolean> exists(String address) {
+        return db.sql("SELECT 1 FROM mail_lists WHERE address = :a").bind("a", address.toLowerCase(Locale.ROOT))
+                .map((row, meta) -> true).one().defaultIfEmpty(false);
+    }
+
+    public Flux<MailList> all() {
+        return db.sql("SELECT id, address, folder, description, open_to_outside FROM mail_lists ORDER BY address")
+                .map((row, meta) -> new MailList(row.get("id", Long.class), row.get("address", String.class),
+                        row.get("folder", String.class), row.get("description", String.class),
+                        Boolean.TRUE.equals(row.get("open_to_outside", Boolean.class)), List.of()))
+                .all()
+                .concatMap(this::withMembers);
+    }
+
+    /** Lists this mailbox is a member of (shown to the mailbox owner). */
+    public Flux<String> listsOf(Long userId) {
+        return db.sql("SELECT l.address FROM mail_lists l JOIN mail_list_members m ON m.list_id = l.id "
+                        + "WHERE m.user_id = :u ORDER BY l.address")
+                .bind("u", userId).map((row, meta) -> row.get("address", String.class)).all();
+    }
+
+    /**
+     * Creates or replaces the list: settings and the exact member set. Members are mailbox ids (checked by the caller).
+     */
+    @Transactional
+    public Mono<MailList> save(String address, String folder, String description, boolean openToOutside,
+                               Collection<Long> memberIds) {
+        String a = address.toLowerCase(Locale.ROOT);
+        var insert = db.sql("INSERT INTO mail_lists (address, folder, description, open_to_outside) "
+                        + "VALUES (:a, :f, :d, :o) ON CONFLICT (address) DO UPDATE "
+                        + "SET folder = EXCLUDED.folder, description = EXCLUDED.description, "
+                        + "open_to_outside = EXCLUDED.open_to_outside RETURNING id")
+                .bind("a", a).bind("o", openToOutside);
+        insert = folder == null ? insert.bindNull("f", String.class) : insert.bind("f", folder);
+        insert = description == null ? insert.bindNull("d", String.class) : insert.bind("d", description);
+        return insert.map((row, meta) -> row.get("id", Long.class)).one()
+                .flatMap(id -> db.sql("DELETE FROM mail_list_members WHERE list_id = :l").bind("l", id).then()
+                        .thenMany(Flux.fromIterable(memberIds).distinct()
+                                .concatMap(member -> db.sql("INSERT INTO mail_list_members (list_id, user_id) VALUES (:l, :u)")
+                                        .bind("l", id).bind("u", member).then()))
+                        .then(find(a)));
+    }
+
+    public Mono<Boolean> delete(String address) {
+        return db.sql("DELETE FROM mail_lists WHERE address = :a").bind("a", address.toLowerCase(Locale.ROOT))
+                .fetch().rowsUpdated().map(n -> n > 0);
+    }
+
+    /** Takes the mailbox out of every list (mailbox switched off / role removed in Jambotron). */
+    public Mono<Long> removeEverywhere(Long userId) {
+        return db.sql("DELETE FROM mail_list_members WHERE user_id = :u").bind("u", userId).fetch().rowsUpdated();
+    }
+
+    private Mono<MailList> withMembers(MailList list) {
+        return db.sql("SELECT u.email FROM mail_list_members m JOIN users u ON u.id = m.user_id "
+                        + "WHERE m.list_id = :l ORDER BY u.email")
+                .bind("l", list.id()).map((row, meta) -> row.get("email", String.class)).all().collectList()
+                .map(members -> new MailList(list.id(), list.address(), list.folder(), list.description(),
+                        list.openToOutside(), members));
+    }
+}

backend/src/main/java/com/mailserver/service/MailService.java

@@ -162,6 +162,34 @@ public class MailService {
                 .switchIfEmpty(Mono.error(badRequest("System folders cannot be renamed or deleted")));
     }
 
+    private static final java.util.regex.Pattern DELIVERY_FOLDER = java.util.regex.Pattern.compile("[A-Za-z0-9][A-Za-z0-9._-]{0,49}");
+
+    /**
+     * A "+tag" / list folder that may be used as a folder name, or null (→ INBOX). A sender never puts mail into
+     * a system folder (Spam, Trash, Sent …) this way.
+     */
+    static String deliveryFolderName(String raw) {
+        if (raw == null || !DELIVERY_FOLDER.matcher(raw).matches() || SYSTEM_FOLDERS.stream().anyMatch(raw::equalsIgnoreCase)) {
+            return null;
+        }
+        return raw;
+    }
+
+    /** The folder with this name (any case), created as an own folder when missing; two at once — one wins. */
+    private Mono<Folder> deliveryFolder(Long userId, String name) {
+        Mono<Folder> existing = folderRepository.findByUserId(userId)
+                .filter(folder -> folder.getName().equalsIgnoreCase(name))
+                .next();
+        return existing.switchIfEmpty(Mono.defer(() -> {
+            Folder folder = new Folder();
+            folder.setUserId(userId);
+            folder.setName(name);
+            folder.setCreatedAt(Instant.now());
+            return folderRepository.save(folder)
+                    .onErrorResume(org.springframework.dao.DataIntegrityViolationException.class, e -> existing);
+        }));
+    }
+
     private Mono<Folder> systemFolder(Long userId, String name) {
         return folderRepository.findByUserIdAndName(userId, name)
                 .switchIfEmpty(Mono.error(new IllegalStateException(name + " folder not found")));
@@ -253,12 +281,25 @@ public class MailService {
     public Mono<Message> receiveMessage(String senderEmail, String senderName, String recipientEmail,
                                String subject, String body, boolean isHtml, boolean externalSpamFlag,
                                String toHeader, String ccHeader) {
+        return receiveMessage(senderEmail, senderName, recipientEmail, subject, body, isHtml, externalSpamFlag,
+                toHeader, ccHeader, null);
+    }
+
+    /**
+     * @param folder own folder for the message ("+tag" of the address, folder of a mailing list), created when
+     *               missing; null or not a valid folder name — INBOX. Spam still goes to Spam.
+     */
+    public Mono<Message> receiveMessage(String senderEmail, String senderName, String recipientEmail,
+                               String subject, String body, boolean isHtml, boolean externalSpamFlag,
+                               String toHeader, String ccHeader, String targetFolder) {
         return userRepository.findByEmail(recipientEmail)
                 .switchIfEmpty(Mono.error(new IllegalArgumentException("Recipient not found: " + recipientEmail)))
                 .flatMap(recipient -> spamFilterService.isBlacklisted(recipient.getId(), senderEmail)
                         .flatMap(blacklisted -> {
                             boolean isSpam = blacklisted || externalSpamFlag;
-                            return systemFolder(recipient.getId(), isSpam ? "Spam" : "INBOX")
+                            String own = isSpam ? null : deliveryFolderName(targetFolder);
+                            return (own == null ? systemFolder(recipient.getId(), isSpam ? "Spam" : "INBOX")
+                                    : deliveryFolder(recipient.getId(), own))
                                     .flatMap(folder -> {
                                         Message message = new Message();
                                         message.setFolderId(folder.getId());
@@ -439,6 +480,7 @@ public class MailService {
         resp.setMessageSize(message.getMessageSize());
         resp.setReceivedAt(message.getReceivedAt());
         resp.setFolderId(message.getFolderId());
+        resp.setAnsweredBy(message.getAnsweredBy());
         return resp;
     }
 

backend/src/main/java/com/mailserver/service/MailboxAccess.java

@@ -0,0 +1,129 @@
+package com.mailserver.service;
+
+import com.mailserver.domain.User;
+import com.mailserver.repository.UserRepository;
+import org.springframework.r2dbc.core.DatabaseClient;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+import java.util.Collection;
+import java.util.Locale;
+
+/**
+ * Several mailboxes for one login (V7): own, shared ones it is a MEMBER of, ATTACHED ones (by their password).
+ * One rule for the web client, SMTP and IMAP; in mail programs another mailbox is
+ * {@code mailbox*login} with the login's password (the Dovecot "master user" form).
+ */
+@Service
+public class MailboxAccess {
+
+    public static final String MEMBER = "MEMBER";
+    public static final String ATTACHED = "ATTACHED";
+
+    /** @param kind OWN, MEMBER or ATTACHED; unread — INBOX and own folders (not Spam/Trash/Sent/Drafts) */
+    public record Entry(String email, String displayName, String kind, boolean shared, long unread) {
+    }
+
+    private final DatabaseClient db;
+    private final UserRepository users;
+    private final UserService userService;
+
+    public MailboxAccess(DatabaseClient db, UserRepository users, UserService userService) {
+        this.db = db;
+        this.users = users;
+        this.userService = userService;
+    }
+
+    /**
+     * Login for SMTP / IMAP: {@code login} or {@code mailbox*login} + the login's password → the mailbox the
+     * session works with, or null. A shared mailbox never logs in by itself.
+     */
+    public User login(String username, String password) {
+        String name = username.trim().toLowerCase(Locale.ROOT);
+        int star = name.indexOf('*');
+        String mailbox = star < 0 ? name : name.substring(0, star);
+        String login = star < 0 ? name : name.substring(star + 1);
+        User user = users.findByEmail(login).block();
+        if (user == null || !user.isActive() || user.isShared() || !userService.checkPassword(user, password)) {
+            return null;
+        }
+        if (mailbox.equals(login)) {
+            return user;
+        }
+        User target = users.findByEmail(mailbox).block();
+        return target != null && target.isActive() && Boolean.TRUE.equals(has(target.getId(), user.getId()).block())
+                ? target : null;
+    }
+
+    /** The login may open this mailbox (own or by access). */
+    public Mono<Boolean> has(Long mailboxId, Long userId) {
+        if (mailboxId.equals(userId)) {
+            return Mono.just(true);
+        }
+        return db.sql("SELECT 1 FROM mailbox_access WHERE mailbox_id = :m AND user_id = :u")
+                .bind("m", mailboxId).bind("u", userId).map((row, meta) -> true).one().defaultIfEmpty(false);
+    }
+
+    /** Own mailbox first, then the others by address. */
+    public Flux<Entry> mailboxes(User login) {
+        Mono<Entry> own = unread(login.getId()).map(n -> new Entry(login.getEmail(), login.getDisplayName(), "OWN", false, n));
+        Flux<Entry> others = db.sql("SELECT u.id, u.email, u.display_name, u.is_shared, a.kind FROM mailbox_access a "
+                        + "JOIN users u ON u.id = a.mailbox_id WHERE a.user_id = :u AND u.is_active ORDER BY u.email")
+                .bind("u", login.getId())
+                .map((row, meta) -> new Object[]{row.get("id", Long.class), row.get("email", String.class),
+                        row.get("display_name", String.class), Boolean.TRUE.equals(row.get("is_shared", Boolean.class)),
+                        row.get("kind", String.class)})
+                .all()
+                .concatMap(r -> unread((Long) r[0]).map(n -> new Entry((String) r[1], (String) r[2], (String) r[4], (Boolean) r[3], n)));
+        return own.flux().concatWith(others);
+    }
+
+    public Mono<Long> unread(Long mailboxId) {
+        return db.sql("SELECT COUNT(*) AS n FROM messages m JOIN folders f ON f.id = m.folder_id "
+                        + "WHERE f.user_id = :u AND NOT m.is_read AND NOT m.is_deleted AND (NOT f.is_system OR f.name = 'INBOX')")
+                .bind("u", mailboxId).map((row, meta) -> row.get("n", Long.class)).one().defaultIfEmpty(0L);
+    }
+
+    public Mono<Void> grant(Long mailboxId, Long userId, String kind) {
+        return db.sql("INSERT INTO mailbox_access (mailbox_id, user_id, kind) VALUES (:m, :u, :k) "
+                        + "ON CONFLICT (mailbox_id, user_id) DO NOTHING")
+                .bind("m", mailboxId).bind("u", userId).bind("k", kind).then();
+    }
+
+    public Mono<Boolean> revoke(Long mailboxId, Long userId) {
+        return db.sql("DELETE FROM mailbox_access WHERE mailbox_id = :m AND user_id = :u")
+                .bind("m", mailboxId).bind("u", userId).fetch().rowsUpdated().map(n -> n > 0);
+    }
+
+    /** Exactly these MEMBERs (ATTACHED ones stay — they know the password). */
+    @Transactional
+    public Mono<Void> setMembers(Long mailboxId, Collection<Long> memberIds) {
+        return db.sql("DELETE FROM mailbox_access WHERE mailbox_id = :m AND kind = :k").bind("m", mailboxId).bind("k", MEMBER).then()
+                .thenMany(Flux.fromIterable(memberIds).distinct().filter(id -> !id.equals(mailboxId))
+                        .concatMap(id -> db.sql("INSERT INTO mailbox_access (mailbox_id, user_id, kind) VALUES (:m, :u, :k) "
+                                        + "ON CONFLICT (mailbox_id, user_id) DO UPDATE SET kind = EXCLUDED.kind")
+                                .bind("m", mailboxId).bind("u", id).bind("k", MEMBER).then()))
+                .then();
+    }
+
+    public Flux<String> members(Long mailboxId) {
+        return db.sql("SELECT u.email FROM mailbox_access a JOIN users u ON u.id = a.user_id "
+                        + "WHERE a.mailbox_id = :m AND a.kind = :k ORDER BY u.email")
+                .bind("m", mailboxId).bind("k", MEMBER).map((row, meta) -> row.get("email", String.class)).all();
+    }
+
+    /** The login loses every MEMBER access (role removed in Jambotron); ATTACHED stays with the mailbox owner's say. */
+    public Mono<Long> removeEverywhere(Long userId) {
+        return db.sql("DELETE FROM mailbox_access WHERE user_id = :u AND kind = :k").bind("u", userId).bind("k", MEMBER)
+                .fetch().rowsUpdated();
+    }
+
+    /** Reply from the web client: the original is answered, and by whom. */
+    public Mono<Void> markAnswered(Long messageId, Long mailboxId, String by) {
+        return db.sql("UPDATE messages SET is_answered = TRUE, answered_by = :b WHERE id = :id "
+                        + "AND folder_id IN (SELECT id FROM folders WHERE user_id = :u)")
+                .bind("b", by).bind("id", messageId).bind("u", mailboxId).then();
+    }
+}

backend/src/main/java/com/mailserver/service/SubmissionService.java

@@ -50,9 +50,11 @@ public class SubmissionService {
     private final MailService mailService;
     private final MailRouter router;
     private final String hostname;
+    private final MailboxAccess access;
 
     public SubmissionService(UserRepository users, MailService mailService, MailRouter router,
-                             @Value("${mailserver.smtp.hostname:localhost}") String hostname) {
+                             @Value("${mailserver.smtp.hostname:localhost}") String hostname, MailboxAccess access) {
+        this.access = access;
         this.users = users;
         this.mailService = mailService;
         this.router = router;
@@ -60,6 +62,11 @@ public class SubmissionService {
     }
 
     public Mono<MessageResponse> send(String fromEmail, SendRequest request) {
+        return send(fromEmail, fromEmail, request);
+    }
+
+    /** @param login who sends (the member for a shared mailbox) — recorded as «answered by» on the original */
+    public Mono<MessageResponse> send(String fromEmail, String login, SendRequest request) {
         List<String> to = addresses(request.getTo());
         List<String> cc = addresses(request.getCc());
         cc.removeAll(to);
@@ -78,7 +85,9 @@ public class SubmissionService {
                                 .subscribeOn(Schedulers.boundedElastic()))
                         .flatMap(messageId -> mailService.saveSent(user, String.join(", ", to), String.join(", ", cc),
                                 request.getSubject(), request.getBody(), request.isHtml(), messageId))
-                        .flatMap(sent -> (draftId == null ? Mono.<Void>empty() : mailService.finishDraft(draftId, sent.getId()))
+                        .flatMap(sent -> (request.getReplyToId() == null ? Mono.<Void>empty()
+                                : access.markAnswered(request.getReplyToId(), user.getId(), login))
+                                .then(draftId == null ? Mono.<Void>empty() : mailService.finishDraft(draftId, sent.getId()))
                                 .then(mailService.getMessage(sent.getId(), user.getId()))));
     }
 
@@ -88,10 +97,10 @@ public class SubmissionService {
         for (String address : concat(to, cc)) {
             SmtpBackend.Route route = router.route(address, user.getEmail());
             switch (route) {
-                case LOCAL, OUTBOUND -> recipients.add(new SmtpBackend.Recipient(address, route));
+                case LOCAL, OUTBOUND, TRAP -> recipients.add(new SmtpBackend.Recipient(address, route));
                 case UNKNOWN_USER -> throw MailService.badRequest("No such mailbox: " + address);
                 case OUTBOUND_DISABLED -> throw MailService.badRequest("Sending outside is disabled on this server: " + address);
-                case RELAY_DENIED -> throw new IllegalStateException("logged-in user denied relay");
+                case RELAY_DENIED, LIST_CLOSED -> throw new IllegalStateException("logged-in user denied: " + route);
             }
         }
         String messageId = UUID.randomUUID() + "@" + hostname;

backend/src/main/java/com/mailserver/service/UserService.java

@@ -74,6 +74,40 @@ public class UserService {
         return userRepository.save(user).then();
     }
 
+    /** The mailbox, or empty (no error). */
+    public Mono<User> findOptional(String email) {
+        return userRepository.findByEmail(email.toLowerCase(java.util.Locale.ROOT));
+    }
+
+    public Flux<User> all() {
+        return userRepository.findAll();
+    }
+
+    public Mono<User> byId(Long id) {
+        return userRepository.findById(id);
+    }
+
+    /** Administrator sets a new password (Settings → Mailboxes): no current password needed. */
+    public Mono<User> setPassword(User user, String newPassword) {
+        user.setPassword(passwordEncoder.encode(newPassword));
+        return userRepository.save(user);
+    }
+
+    public Mono<User> setActive(User user, boolean active) {
+        user.setActive(active);
+        return userRepository.save(user);
+    }
+
+    public Mono<User> setShared(User user, boolean shared) {
+        user.setShared(shared);
+        return userRepository.save(user);
+    }
+
+    public Mono<User> setTrap(User user, boolean trap) {
+        user.setTrap(trap);
+        return userRepository.save(user);
+    }
+
     public Mono<User> updateDisplayName(User user, String displayName) {
         user.setDisplayName(displayName.trim());
         return userRepository.save(user);

backend/src/main/java/com/mailserver/smtp/MailRouter.java

@@ -7,16 +7,26 @@ import com.mailserver.domain.User;
 import com.mailserver.repository.UserRepository;
 import com.mailserver.service.DkimService;
 import com.mailserver.service.LocalDelivery;
+import com.mailserver.service.MailLists;
+import com.mailserver.service.MailboxAccess;
 import com.mailserver.service.UserService;
 import org.springframework.stereotype.Service;
 
+import java.util.LinkedHashSet;
 import java.util.Locale;
+import java.util.Set;
 
 /**
  * Where mail goes — one rule for SMTP and for the web client:
- * an existing mailbox of our domain → that mailbox; catch-all set → everything else into the catch-all mailbox
+ * <ul>
- * (nothing goes outside, existing mailboxes still get their own mail); otherwise our domain without such a mailbox →
+ *   <li>a mailbox of ours → that mailbox; {@code bob+prod@} → bob's folder "prod" (created on first mail);</li>
- * "no such user", someone else's domain → the delivery queue, only for a logged-in sender (never an open relay).
+ *   <li>a mailing list of ours ({@code alerts-prod@}) → a copy to every member, into the list's folder
+ *       (or the "+tag" folder); a closed list takes mail only from logged-in senders;</li>
+ *   <li>a TRAP sender (staging@) and an address that is not ours → nothing leaves: one copy into the sender's INBOX
+ *       (our own mailboxes and lists still get their mail);</li>
+ *   <li>catch-all set → everything else into the catch-all mailbox; otherwise our domain → "no such user",
+ *       someone else's domain → the delivery queue, only for a logged-in sender (never an open relay).</li>
+ * </ul>
  */
 @Service
 public class MailRouter implements SmtpBackend {
@@ -28,9 +38,13 @@ public class MailRouter implements SmtpBackend {
     private final OutboundQueue queue;
     private final DkimService dkim;
     private final SmtpDeliveryClient client;
+    private final MailLists lists;
+    private final MailboxAccess access;
 
     public MailRouter(MailDomains domains, UserRepository users, UserService userService, LocalDelivery localDelivery,
-                      OutboundQueue queue, DkimService dkim, SmtpDeliveryClient client) {
+                      OutboundQueue queue, DkimService dkim, SmtpDeliveryClient client, MailLists lists,
+                      MailboxAccess access) {
+        this.access = access;
         this.domains = domains;
         this.users = users;
         this.userService = userService;
@@ -38,18 +52,29 @@ public class MailRouter implements SmtpBackend {
         this.queue = queue;
         this.dkim = dkim;
         this.client = client;
+        this.lists = lists;
     }
 
     @Override
-    public boolean authenticate(String username, String password) {
+    public String authenticate(String username, String password) {
-        User user = users.findByEmail(username.toLowerCase(Locale.ROOT)).block();
+        User mailbox = access.login(username, password);
-        return user != null && user.isActive() && userService.checkPassword(user, password);
+        return mailbox == null ? null : mailbox.getEmail();
     }
 
     @Override
     public Route route(String recipient, String authenticatedUser) {
-        if (domains.isLocal(recipient) && mailboxExists(recipient)) {
+        if (domains.isLocal(recipient)) {
-            return Route.LOCAL;
+            String base = MailDomains.baseOf(recipient);
+            if (mailboxExists(recipient) || mailboxExists(base)) {
+                return Route.LOCAL;
+            }
+            MailLists.MailList list = lists.find(base).block();
+            if (list != null) {
+                return list.openToOutside() || authenticatedUser != null ? Route.LOCAL : Route.LIST_CLOSED;
+            }
+        }
+        if (isTrap(authenticatedUser)) {
+            return Route.TRAP;
         }
         if (domains.catchAll() != null) {
             return Route.LOCAL;
@@ -66,13 +91,13 @@ public class MailRouter implements SmtpBackend {
     @Override
     public void accept(Envelope envelope, byte[] message) throws Exception {
         boolean trusted = envelope.authenticatedUser() != null;
+        // one copy per mailbox + folder, even when an address and a list both lead there
+        Set<Target> targets = new LinkedHashSet<>();
         byte[] signed = null;
         for (Recipient recipient : envelope.recipients()) {
             switch (recipient.route()) {
-                case LOCAL -> {
+                case LOCAL -> targets.addAll(targets(recipient.address()));
-                    String mailbox = mailbox(recipient.address());
+                case TRAP -> targets.add(new Target(envelope.authenticatedUser().toLowerCase(Locale.ROOT), null));
-                    localDelivery.deliver(message, mailbox, envelope.remoteIp(), envelope.mailFrom(), trusted);
-                }
                 case OUTBOUND -> {
                     if (signed == null) {
                         signed = dkim.sign(message);
@@ -82,14 +107,56 @@ public class MailRouter implements SmtpBackend {
                 default -> throw new IllegalStateException("Recipient was not accepted: " + recipient);
             }
         }
+        for (Target target : targets) {
+            localDelivery.deliver(message, target.mailbox(), target.folder(), envelope.remoteIp(), envelope.mailFrom(), trusted);
+        }
     }
 
-    /** Mailbox that stores mail to this address: its own if it exists here, otherwise the catch-all one. */
+    /** Mailbox + folder (null — INBOX) that store mail to a local address. */
-    String mailbox(String address) {
+    record Target(String mailbox, String folder) {
-        if (domains.catchAll() == null || (domains.isLocal(address) && mailboxExists(address))) {
+    }
-            return address;
+
+    Set<Target> targets(String address) {
+        Set<Target> result = new LinkedHashSet<>();
+        String lower = address.toLowerCase(Locale.ROOT);
+        if (domains.isLocal(lower)) {
+            if (mailboxExists(lower)) {
+                result.add(new Target(lower, null));
+                return result;
+            }
+            String base = MailDomains.baseOf(lower);
+            String tag = MailDomains.tagOf(address);
+            if (mailboxExists(base)) {
+                result.add(new Target(base, tag));
+                return result;
+            }
+            MailLists.MailList list = lists.find(base).block();
+            if (list != null) {
+                for (String member : list.members()) {
+                    result.add(new Target(member, tag != null ? tag : list.folder()));
+                }
+                return result;
+            }
         }
-        return domains.catchAll();
+        if (domains.catchAll() != null) {
+            result.add(new Target(domains.catchAll(), null));
+        }
+        return result;
+    }
+
+    /** Mailbox that stores mail to this address: its own (without "+tag") if it exists here, otherwise the catch-all one. */
+    String mailbox(String address) {
+        Set<Target> found = targets(address);
+        return found.isEmpty() ? address : found.iterator().next().mailbox();
+    }
+
+    /** The logged-in sender is a trap mailbox. */
+    boolean isTrap(String authenticatedUser) {
+        if (authenticatedUser == null) {
+            return false;
+        }
+        User user = users.findByEmail(authenticatedUser.toLowerCase(Locale.ROOT)).block();
+        return user != null && user.isTrap();
     }
 
     private boolean mailboxExists(String address) {

backend/src/main/java/com/mailserver/smtp/ReloadingKeyManager.java

@@ -0,0 +1,194 @@
+package com.mailserver.smtp;
+
+import org.bouncycastle.asn1.pkcs.PrivateKeyInfo;
+import org.bouncycastle.openssl.PEMKeyPair;
+import org.bouncycastle.openssl.PEMParser;
+import org.bouncycastle.openssl.jcajce.JcaPEMKeyConverter;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.net.ssl.SSLEngine;
+import javax.net.ssl.X509ExtendedKeyManager;
+import java.io.InputStream;
+import java.io.Reader;
+import java.net.Socket;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.attribute.FileTime;
+import java.security.Principal;
+import java.security.PrivateKey;
+import java.security.cert.CertificateFactory;
+import java.security.cert.X509Certificate;
+import java.time.Clock;
+import java.time.Duration;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * Server certificate and key from PEM files, read again when the files change — a Let's Encrypt certificate
+ * renewed on disk (lego, certbot) is picked up without a restart, for STARTTLS and implicit TLS alike: the JDK
+ * asks the key manager on every handshake. The files are checked at most once per {@code interval}; a file
+ * that cannot be read (a renewal half written) keeps the previous certificate and is tried again next time.
+ * <p>
+ * Key: PKCS#8 ({@code PRIVATE KEY}) or the traditional {@code RSA PRIVATE KEY} / {@code EC PRIVATE KEY} that
+ * lego and certbot write. Each loaded pair gets its own alias, so a handshake that asks for the chain and then
+ * for the key never mixes two generations.
+ */
+public final class ReloadingKeyManager extends X509ExtendedKeyManager {
+
+    private static final Logger log = LoggerFactory.getLogger(ReloadingKeyManager.class);
+    private static final String ALIAS_PREFIX = "mail-";
+
+    record Material(String alias, X509Certificate[] chain, PrivateKey key, FileTime certTime, FileTime keyTime) {
+    }
+
+    private final Path certFile;
+    private final Path keyFile;
+    private final Duration interval;
+    private final Clock clock;
+    /** The current pair and the one before it (a handshake may still hold its alias) */
+    private final Map<String, Material> byAlias = new ConcurrentHashMap<>();
+    private volatile Material current;
+    private volatile long checkedAt;
+    private int generation;
+
+    public ReloadingKeyManager(Path certFile, Path keyFile, Duration interval, Clock clock) throws Exception {
+        this.certFile = certFile;
+        this.keyFile = keyFile;
+        this.interval = interval;
+        this.clock = clock;
+        install(load());
+        this.checkedAt = clock.millis();
+    }
+
+    /** The pair to use now; reads the files again when the interval has passed and they changed */
+    Material material() {
+        long now = clock.millis();
+        if (now - checkedAt >= interval.toMillis()) {
+            synchronized (this) {
+                if (now - checkedAt >= interval.toMillis()) {
+                    checkedAt = now;
+                    reloadIfChanged();
+                }
+            }
+        }
+        return current;
+    }
+
+    private void reloadIfChanged() {
+        Material old = current;
+        try {
+            if (Files.getLastModifiedTime(certFile).equals(old.certTime())
+                    && Files.getLastModifiedTime(keyFile).equals(old.keyTime())) {
+                return;
+            }
+            Material fresh = load();
+            install(fresh);
+            log.info("TLS: certificate {} reloaded, valid until {}", certFile, fresh.chain()[0].getNotAfter());
+        } catch (Exception e) {
+            log.warn("TLS: cannot read {} / {} ({}), keeping the certificate valid until {}",
+                    certFile, keyFile, e.toString(), old.chain()[0].getNotAfter());
+        }
+    }
+
+    private synchronized void install(Material material) {
+        Material previous = current;
+        byAlias.keySet().removeIf(alias -> previous == null || !alias.equals(previous.alias()));
+        byAlias.put(material.alias(), material);
+        current = material;
+    }
+
+    private Material load() throws Exception {
+        FileTime certTime = Files.getLastModifiedTime(certFile);
+        FileTime keyTime = Files.getLastModifiedTime(keyFile);
+        X509Certificate[] chain;
+        try (InputStream in = Files.newInputStream(certFile)) {
+            chain = CertificateFactory.getInstance("X.509").generateCertificates(in).stream()
+                    .map(X509Certificate.class::cast).toArray(X509Certificate[]::new);
+        }
+        if (chain.length == 0) {
+            throw new IllegalStateException("no certificate in " + certFile);
+        }
+        PrivateKey key = readKey(keyFile);
+        if (!chain[0].getPublicKey().getAlgorithm().equals(key.getAlgorithm())) {
+            throw new IllegalStateException("the key in " + keyFile + " is " + key.getAlgorithm()
+                    + ", the certificate is " + chain[0].getPublicKey().getAlgorithm());
+        }
+        String alias;
+        synchronized (this) {
+            alias = ALIAS_PREFIX + (++generation);
+        }
+        return new Material(alias, chain, key, certTime, keyTime);
+    }
+
+    static PrivateKey readKey(Path file) throws Exception {
+        try (Reader reader = Files.newBufferedReader(file, StandardCharsets.US_ASCII);
+             PEMParser parser = new PEMParser(reader)) {
+            Object object;
+            while ((object = parser.readObject()) != null) {
+                JcaPEMKeyConverter converter = new JcaPEMKeyConverter();
+                if (object instanceof PrivateKeyInfo info) {
+                    return converter.getPrivateKey(info);
+                }
+                if (object instanceof PEMKeyPair pair) {
+                    return converter.getPrivateKey(pair.getPrivateKeyInfo()); // SEC1 may come without the public part
+                }
+                // EC PARAMETERS before EC PRIVATE KEY (openssl ecparam -genkey) — skip
+            }
+        }
+        throw new IllegalStateException("no private key in " + file);
+    }
+
+    private String serverAlias(String keyType) {
+        Material material = material();
+        String algorithm = material.key().getAlgorithm();
+        boolean fits = keyType == null || keyType.equalsIgnoreCase(algorithm)
+                || ("RSA".equals(algorithm) && keyType.equalsIgnoreCase("RSASSA-PSS"))
+                || ("EC".equals(algorithm) && keyType.toUpperCase().startsWith("EC"));
+        return fits ? material.alias() : null;
+    }
+
+    @Override
+    public String chooseServerAlias(String keyType, Principal[] issuers, Socket socket) {
+        return serverAlias(keyType);
+    }
+
+    @Override
+    public String chooseEngineServerAlias(String keyType, Principal[] issuers, SSLEngine engine) {
+        return serverAlias(keyType);
+    }
+
+    @Override
+    public String[] getServerAliases(String keyType, Principal[] issuers) {
+        String alias = serverAlias(keyType);
+        return alias == null ? null : new String[]{alias};
+    }
+
+    @Override
+    public X509Certificate[] getCertificateChain(String alias) {
+        Material material = alias == null ? null : byAlias.get(alias);
+        return material == null ? null : material.chain().clone();
+    }
+
+    @Override
+    public PrivateKey getPrivateKey(String alias) {
+        Material material = alias == null ? null : byAlias.get(alias);
+        return material == null ? null : material.key();
+    }
+
+    @Override
+    public String[] getClientAliases(String keyType, Principal[] issuers) {
+        return null;
+    }
+
+    @Override
+    public String chooseClientAlias(String[] keyType, Principal[] issuers, Socket socket) {
+        return null;
+    }
+
+    @Override
+    public String chooseEngineClientAlias(String[] keyType, Principal[] issuers, SSLEngine engine) {
+        return null;
+    }
+}

backend/src/main/java/com/mailserver/smtp/SmtpBackend.java

@@ -10,8 +10,12 @@ public interface SmtpBackend {
 
     /** Where a recipient goes, decided at RCPT TO. */
     enum Route {
-        /** A mailbox of ours (or the catch-all mailbox) — store it. */
+        /** A mailbox or mailing list of ours (or the catch-all mailbox) — store it. */
         LOCAL,
+        /** The sender is a trap mailbox and the address is not ours: one copy into the sender's own INBOX. */
+        TRAP,
+        /** A mailing list of ours that takes mail only from logged-in senders. */
+        LIST_CLOSED,
         /** Someone else's address, sender is logged in — queue for delivery. */
         OUTBOUND,
         /** Address of our domain that does not exist. */
@@ -28,8 +32,11 @@ public interface SmtpBackend {
     record Envelope(String remoteIp, String helo, String mailFrom, String authenticatedUser, List<Recipient> recipients) {
     }
 
-    /** true — the address and password belong to an active mailbox. */
+    /**
-    boolean authenticate(String username, String password);
+     * {@code login} or {@code mailbox*login} with the login's password → the mailbox address the session works as,
+     * or null.
+     */
+    String authenticate(String username, String password);
 
     Route route(String recipient, String authenticatedUser);
 

backend/src/main/java/com/mailserver/smtp/SmtpServer.java

@@ -1,5 +1,6 @@
 package com.mailserver.smtp;
 
+import com.mailserver.security.LoginGuard;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufUtil;
 import io.netty.channel.ChannelHandlerContext;
@@ -54,6 +55,8 @@ public class SmtpServer {
     static final int MAX_LINE = 64 * 1024;
     static final int MAX_RECIPIENTS = 100;
     private static final int MAX_BAD_COMMANDS = 20;
+    /** Wrong passwords in one connection before it is closed. */
+    private static final int MAX_AUTH_FAILURES = 3;
     // Compared by identity: TLS starts right after exactly this reply is written
     private static final String STARTTLS_READY = new String("220 2.0.0 Ready to start TLS\r\n");
 
@@ -84,11 +87,17 @@ public class SmtpServer {
 
     private final Settings settings;
     private final SmtpBackend backend;
+    private final LoginGuard guard;
     private DisposableServer server;
 
     public SmtpServer(Settings settings, SmtpBackend backend) {
+        this(settings, backend, LoginGuard.disabled());
+    }
+
+    public SmtpServer(Settings settings, SmtpBackend backend, LoginGuard guard) {
         this.settings = settings;
         this.backend = backend;
+        this.guard = guard;
     }
 
     public void start() {
@@ -183,6 +192,7 @@ public class SmtpServer {
         final ByteArrayOutputStream data = new ByteArrayOutputStream();
         boolean dataTooBig;
         int badCommands;
+        int authFailures;
         volatile boolean closing;
 
         Session(String remoteIp, boolean tls) {
@@ -356,16 +366,33 @@ public class SmtpServer {
 
         private Mono<String> checkPassword(String user, String password) {
             String username = user.trim().toLowerCase(Locale.ROOT);
-            return blocking(() -> backend.authenticate(username, password))
+            Duration wait = guard.retryAfter(remoteIp, username);
-                    .map(ok -> {
+            if (!wait.isZero()) {
-                        if (ok) {
+                // Blocked: the password is not even checked, the connection is closed
-                            authenticatedUser = username;
+                log.warn("SMTP {}: login as {} refused, blocked for {}", remoteIp, username, LoginGuard.human(wait));
-                            log.info("SMTP {}: authenticated as {}", remoteIp, username);
+                closing = true;
-                            return "235 2.7.0 Authentication successful\r\n";
+                return reply("421 4.7.0 Too many failed logins, try again in " + LoginGuard.human(wait));
+            }
+            return blocking(() -> java.util.Optional.ofNullable(backend.authenticate(username, password)))
+                    .flatMap(found -> {
+                        if (found.isPresent()) {
+                            guard.success(remoteIp, username);
+                            authenticatedUser = found.get();
+                            log.info("SMTP {}: authenticated as {}{}", remoteIp, found.get(),
+                                    found.get().equalsIgnoreCase(username) ? "" : " (login " + username + ")");
+                            return Mono.just("235 2.7.0 Authentication successful\r\n");
                         }
+                        guard.failure(remoteIp, username);
                         log.warn("SMTP {}: authentication failed for {}", remoteIp, username);
                         badCommands++;
-                        return "535 5.7.8 Authentication credentials invalid\r\n";
+                        if (++authFailures >= MAX_AUTH_FAILURES) {
+                            closing = true;
+                        }
+                        String answer = closing
+                                ? "535 5.7.8 Authentication credentials invalid, closing connection\r\n"
+                                : "535 5.7.8 Authentication credentials invalid\r\n";
+                        Duration delay = guard.failureDelay();
+                        return delay.isZero() ? Mono.just(answer) : Mono.just(answer).delayElement(delay);
                     });
         }
 
@@ -412,7 +439,7 @@ public class SmtpServer {
             String user = authenticatedUser;
             return blocking(() -> backend.route(address, user))
                     .map(route -> switch (route) {
-                        case LOCAL, OUTBOUND -> {
+                        case LOCAL, OUTBOUND, TRAP -> {
                             recipients.add(new SmtpBackend.Recipient(address, route));
                             yield "250 2.1.5 Recipient OK\r\n";
                         }
@@ -422,6 +449,7 @@ public class SmtpServer {
                             yield "550 5.7.1 Relaying denied: authentication required\r\n";
                         }
                         case OUTBOUND_DISABLED -> "550 5.7.1 Outbound delivery is disabled on this server\r\n";
+                        case LIST_CLOSED -> "550 5.7.1 This list takes mail only from logged-in senders\r\n";
                     });
         }
 

backend/src/main/java/com/mailserver/smtp/SmtpTls.java

@@ -22,6 +22,7 @@ import java.security.KeyPair;
 import java.security.KeyPairGenerator;
 import java.security.SecureRandom;
 import java.security.cert.X509Certificate;
+import java.time.Clock;
 import java.time.Duration;
 import java.time.Instant;
 import java.util.Base64;
@@ -30,7 +31,8 @@ import java.util.Date;
 /**
  * Certificate for SMTP TLS (STARTTLS and implicit TLS):
  * <ul>
- *   <li>{@code cert} and {@code key} given (PEM: certificate chain and PKCS#8 key, e.g. from Let's Encrypt) — used as is;</li>
+ *   <li>{@code cert} and {@code key} given (PEM: certificate chain and the key — PKCS#8, RSA or EC, e.g. from Let's Encrypt) —
+ *       used as is and read again when the files change ({@link ReloadingKeyManager}, checked once a minute);</li>
  *   <li>otherwise a self-signed certificate for the server hostname, created once in {@code dir} and reused —
  *       enough for encryption between our own services; other servers deliver over it too (MX delivery does not
  *       check certificates, RFC 7435 opportunistic TLS).</li>
@@ -41,6 +43,7 @@ public final class SmtpTls {
     private static final Logger log = LoggerFactory.getLogger(SmtpTls.class);
     static final String CERT_FILE = "smtp-cert.pem";
     static final String KEY_FILE = "smtp-key.pem";
+    static final Duration RELOAD_CHECK = Duration.ofMinutes(1);
 
     private SmtpTls() {
     }
@@ -67,7 +70,8 @@ public final class SmtpTls {
                 log.info("SMTP TLS: self-signed certificate {}", cert);
             }
         }
-        return SslContextBuilder.forServer(cert.toFile(), key.toFile())
+        // Read again when the files change (a renewed Let's Encrypt certificate) — no restart needed
+        return SslContextBuilder.forServer(new ReloadingKeyManager(cert, key, RELOAD_CHECK, Clock.systemUTC()))
                 .protocols("TLSv1.3", "TLSv1.2")
                 .build();
     }

backend/src/main/java/com/mailserver/util/JwtUtils.java

@@ -18,11 +18,20 @@ public class JwtUtils {
     }
 
     public String generateToken(String email) {
+        return generateToken(email, null);
+    }
+
+    /**
+     * @param by the login that opened this mailbox (shared / attached mailbox, administrator's OPEN), or null —
+     *           the mailbox itself logged in
+     */
+    public String generateToken(String email, String by) {
         Date now = new Date();
         Date expiry = new Date(now.getTime() + EXPIRATION_MS);
 
         return Jwts.builder()
                 .subject(email)
+                .claim("by", by)
                 .issuedAt(now)
                 .expiration(expiry)
                 .signWith(signingKey)
@@ -38,6 +47,12 @@ public class JwtUtils {
         return claims.getSubject();
     }
 
+    /** "by" claim: who opened this mailbox, or null. */
+    public String getByFromToken(String token) {
+        Object by = Jwts.parser().verifyWith(signingKey).build().parseSignedClaims(token).getPayload().get("by");
+        return by == null ? null : by.toString();
+    }
+
     public boolean isValidToken(String token) {
         try {
             Jwts.parser()

backend/src/main/resources/application.properties

@@ -27,8 +27,13 @@ mailserver.catch-all=${MAIL_CATCH_ALL:}
 mailserver.registration.enabled=${MAIL_REGISTRATION:false}
 mailserver.admin.email=${MAIL_ADMIN_EMAIL:}
 mailserver.admin.password=${MAIL_ADMIN_PASSWORD:}
+# Who manages mailboxes (Settings → Mailboxes), comma separated; empty — the first mailbox (admin.email or admin@<first domain>)
+mailserver.admins=${MAIL_ADMINS:}
 # Generated passwords of created mailboxes (first admin, catch-all) are appended here (mode 600); empty — printed to the log once
 mailserver.passwords-file=${MAIL_PASSWORDS_FILE:}
+# Service API for Jambotron (/api/service/**, staff mailboxes and lists); empty — the API is off.
+# In the compose files: generated by secrets-init into the secrets volume (file SERVICE_TOKEN).
+mailserver.service-token=${SERVICE_TOKEN:}
 mailserver.cors.origins=${MAIL_CORS_ORIGINS:}
 
 # Attachments
@@ -47,6 +52,8 @@ mailserver.tls.enabled=${MAIL_TLS:true}
 mailserver.tls.cert-file=${MAIL_TLS_CERT:}
 mailserver.tls.key-file=${MAIL_TLS_KEY:}
 mailserver.tls.dir=${MAIL_TLS_DIR:./tls}
+# Web client + API over HTTPS with the same certificate (public compose: 8443 → 443); 0 — only plain HTTP (server.port)
+mailserver.https.port=${HTTPS_PORT:0}
 mailserver.smtps.port=${SMTPS_PORT:0}
 
 # Outbound: off | mx (straight to recipients' MX, port 25) | smarthost (via a provider, e.g. Resend)
@@ -83,3 +90,15 @@ management.endpoints.web.exposure.include=health
 management.endpoint.health.show-details=never
 
 logging.level.com.mailserver=INFO
+
+# Brute-force protection for SMTP AUTH, IMAP login, web login and password change (one counter for all of them):
+# MAX_PER_IP wrong passwords from one IP within WINDOW → the IP is blocked for BLOCK (each next block twice as long,
+# up to MAX_BLOCK); MAX_PER_ACCOUNT wrong passwords to one mailbox from any IPs → the mailbox is blocked for BLOCK,
+# except for IPs that logged in to it before. TRUSTED_IPS (comma-separated) are never blocked by IP
+mailserver.login-guard.enabled=${LOGIN_GUARD:true}
+mailserver.login-guard.max-per-ip=${LOGIN_GUARD_MAX_PER_IP:10}
+mailserver.login-guard.max-per-account=${LOGIN_GUARD_MAX_PER_ACCOUNT:20}
+mailserver.login-guard.window=${LOGIN_GUARD_WINDOW:15m}
+mailserver.login-guard.block=${LOGIN_GUARD_BLOCK:15m}
+mailserver.login-guard.max-block=${LOGIN_GUARD_MAX_BLOCK:24h}
+mailserver.login-guard.trusted-ips=${LOGIN_GUARD_TRUSTED_IPS:}

backend/src/main/resources/db/migration/V5__trap_mailbox.sql

@@ -0,0 +1,3 @@
+-- Trap mailbox: what it sends is NOT delivered to anyone — every copy lands in its own INBOX (staging@: test mail
+-- of a staging stand never reaches real people). Switched on by an administrator in Settings → MAILBOXES.
+ALTER TABLE users ADD COLUMN is_trap BOOLEAN NOT NULL DEFAULT FALSE;

backend/src/main/resources/db/migration/V6__lists.sql

@@ -0,0 +1,18 @@
+-- Mailing lists (alerts-prod@ …): mail to the list address → a copy into the mailbox of EVERY member,
+-- into the list's folder (created on first mail). Each member has their own copy — their own read/unread.
+-- open_to_outside = false: only logged-in senders (Kuma, Jambotron) may write to the list.
+CREATE TABLE mail_lists (
+    id BIGSERIAL PRIMARY KEY,
+    address VARCHAR(255) UNIQUE NOT NULL,
+    folder VARCHAR(50),
+    description VARCHAR(255),
+    open_to_outside BOOLEAN NOT NULL DEFAULT FALSE,
+    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
+);
+
+CREATE TABLE mail_list_members (
+    list_id BIGINT NOT NULL REFERENCES mail_lists(id) ON DELETE CASCADE,
+    user_id BIGINT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    PRIMARY KEY (list_id, user_id)
+);
+CREATE INDEX idx_mail_list_members_user ON mail_list_members(user_id);

backend/src/main/resources/db/migration/V7__mailbox_access.sql

@@ -0,0 +1,19 @@
+-- Several mailboxes for one login (75.9):
+--   shared mailbox (support@, billing@): no login of its own, members open it from their mailbox; read/unread is
+--   common — a team inbox; answered_by shows who replied;
+--   attached mailbox: a login adds another mailbox it knows the password of.
+ALTER TABLE users ADD COLUMN is_shared BOOLEAN NOT NULL DEFAULT FALSE;
+
+CREATE TABLE mailbox_access (
+    mailbox_id BIGINT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    user_id BIGINT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    -- MEMBER: given by an administrator / Jambotron; ATTACHED: added by the user with the mailbox password
+    kind VARCHAR(10) NOT NULL,
+    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    PRIMARY KEY (mailbox_id, user_id),
+    CHECK (mailbox_id <> user_id)
+);
+CREATE INDEX idx_mailbox_access_user ON mailbox_access(user_id);
+
+-- who answered a message (web client reply; mostly for shared mailboxes)
+ALTER TABLE messages ADD COLUMN answered_by VARCHAR(255);

backend/src/test/java/com/mailserver/config/HttpsConfigTest.java

@@ -0,0 +1,45 @@
+package com.mailserver.config;
+
+import com.mailserver.smtp.SmtpTls;
+import io.netty.handler.ssl.SslContextBuilder;
+import io.netty.handler.ssl.util.InsecureTrustManagerFactory;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+import org.springframework.core.io.buffer.DefaultDataBufferFactory;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.server.reactive.HttpHandler;
+import reactor.core.publisher.Mono;
+import reactor.netty.http.client.HttpClient;
+
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Path;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/** https://mail.jambocheck.com: the web client over HTTPS with the mail certificate. */
+class HttpsConfigTest {
+
+    @Test
+    void servesTheWebAppOverTls(@TempDir Path dir) throws Exception {
+        MailServerConfig.SmtpTlsContext tls = new MailServerConfig.SmtpTlsContext(SmtpTls.serverContext("", "", dir, "localhost"));
+        HttpHandler handler = (request, response) -> {
+            response.setStatusCode(HttpStatus.OK);
+            return response.writeWith(Mono.just(DefaultDataBufferFactory.sharedInstance
+                    .wrap(("hello " + request.getURI().getScheme()).getBytes(StandardCharsets.UTF_8))));
+        };
+        io.netty.handler.ssl.SslContext trustAll = SslContextBuilder.forClient().trustManager(InsecureTrustManagerFactory.INSTANCE).build();
+        HttpsConfig.HttpsServer server = new HttpsConfig.HttpsServer(handler, tls, "127.0.0.1", 0);
+        server.start();
+        try {
+            assertThat(server.isRunning()).isTrue();
+            String body = HttpClient.create()
+                    .secure(spec -> spec.sslContext(trustAll))
+                    .get().uri("https://127.0.0.1:" + server.port() + "/")
+                    .responseContent().aggregate().asString().block();
+            assertThat(body).isEqualTo("hello https");
+        } finally {
+            server.stop();
+        }
+        assertThat(server.isRunning()).isFalse();
+    }
+}

backend/src/test/java/com/mailserver/config/LoginGuardConfigTest.java

@@ -0,0 +1,46 @@
+package com.mailserver.config;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.http.server.reactive.ServerHttpRequest;
+import org.springframework.mock.http.server.reactive.MockServerHttpRequest;
+
+import java.net.InetSocketAddress;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class LoginGuardConfigTest {
+
+    private final LoginGuardConfig.TrustedProxyHeaderTransformer transformer = new LoginGuardConfig.TrustedProxyHeaderTransformer();
+
+    private ServerHttpRequest from(String peer) {
+        return MockServerHttpRequest.post("/api/login")
+                .remoteAddress(new InetSocketAddress(peer, 40000))
+                .header("X-Forwarded-For", "198.51.100.9")
+                .header("X-Forwarded-Proto", "https")
+                .build();
+    }
+
+    @Test
+    void forwardedForIsBelievedFromAPrivateProxy() {
+        ServerHttpRequest request = transformer.apply(from("172.18.0.5"));
+        assertThat(request.getRemoteAddress().getHostString()).isEqualTo("198.51.100.9");
+        assertThat(request.getURI().getScheme()).isEqualTo("https");
+    }
+
+    @Test
+    void forwardedForFromTheInternetIsDropped() {
+        ServerHttpRequest request = transformer.apply(from("203.0.113.7"));
+        assertThat(request.getRemoteAddress().getAddress().getHostAddress()).isEqualTo("203.0.113.7");
+        assertThat(request.getHeaders().containsKey("X-Forwarded-For")).isFalse();
+    }
+
+    @Test
+    void privateRanges() {
+        for (String ip : new String[]{"127.0.0.1", "10.30.0.13", "172.16.0.1", "192.168.1.1", "fd00::1", "::1", "fe80::1"}) {
+            assertThat(LoginGuardConfig.privatePeer(new InetSocketAddress(ip, 1))).as(ip).isTrue();
+        }
+        for (String ip : new String[]{"103.109.235.154", "172.32.0.1", "2001:db8::1", "8.8.8.8"}) {
+            assertThat(LoginGuardConfig.privatePeer(new InetSocketAddress(ip, 1))).as(ip).isFalse();
+        }
+    }
+}

backend/src/test/java/com/mailserver/config/MailDomainsTest.java

@@ -0,0 +1,19 @@
+package com.mailserver.config;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/** "+tag" addresses: the base address is the mailbox, the tag is the folder. */
+class MailDomainsTest {
+
+    @Test
+    void baseAndTag() {
+        assertThat(MailDomains.baseOf("Bob+Prod@Mail.test")).isEqualTo("bob@mail.test");
+        assertThat(MailDomains.tagOf("Bob+Prod@Mail.test")).isEqualTo("Prod");
+        assertThat(MailDomains.baseOf("bob@mail.test")).isEqualTo("bob@mail.test");
+        assertThat(MailDomains.tagOf("bob@mail.test")).isNull();
+        assertThat(MailDomains.tagOf("bob+@mail.test")).isNull();
+        assertThat(MailDomains.tagOf("+x@mail.test")).isNull();
+    }
+}

backend/src/test/java/com/mailserver/controller/AuthenticationControllerTest.java

@@ -0,0 +1,81 @@
+package com.mailserver.controller;
+
+import com.mailserver.config.MailDomains;
+import com.mailserver.domain.User;
+import com.mailserver.dto.LoginRequest;
+import com.mailserver.security.LoginGuard;
+import com.mailserver.service.MailService;
+import com.mailserver.service.UserService;
+import com.mailserver.util.JwtUtils;
+import org.junit.jupiter.api.Test;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.mock.http.server.reactive.MockServerHttpRequest;
+import reactor.core.publisher.Mono;
+
+import java.net.InetSocketAddress;
+import java.time.Duration;
+import java.util.Map;
+import java.util.Set;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+class AuthenticationControllerTest {
+
+    private final UserService users = mock(UserService.class);
+    private final JwtUtils jwt = mock(JwtUtils.class);
+    private final LoginGuard guard = new LoginGuard(new LoginGuard.Settings(true, 3, 100, Duration.ofMinutes(15),
+            Duration.ofMinutes(15), Duration.ofHours(24), Duration.ofDays(30), Set.of(), Duration.ZERO));
+    private final AuthenticationController controller = new AuthenticationController(users, mock(MailService.class), jwt,
+            mock(MailDomains.class), false, guard, mock(com.mailserver.config.MailAdmins.class));
+
+    private final User alice = new User();
+
+    AuthenticationControllerTest() {
+        alice.setEmail("alice@x.test");
+        alice.setPassword("hash");
+        when(users.findByEmail("alice@x.test")).thenReturn(Mono.just(alice));
+        when(users.findByEmail("ghost@x.test")).thenReturn(Mono.empty());
+        when(users.checkPassword(eq(alice), anyString())).thenAnswer(i -> "secret".equals(i.getArgument(1)));
+        when(jwt.generateToken(any())).thenReturn("token");
+    }
+
+    private ResponseEntity<?> login(String ip, String email, String password) {
+        LoginRequest request = new LoginRequest();
+        request.setEmail(email);
+        request.setPassword(password);
+        MockServerHttpRequest http = MockServerHttpRequest.post("/api/login")
+                .remoteAddress(new InetSocketAddress(ip, 40000)).build();
+        return controller.login(Mono.just(request), http).block();
+    }
+
+    @Test
+    void unknownMailboxAndWrongPasswordLookTheSameAndBothCount() {
+        assertThat(login("1.2.3.4", "ghost@x.test", "x").getBody()).isEqualTo(Map.of("error", "Invalid credentials"));
+        assertThat(login("1.2.3.4", "alice@x.test", "x").getBody()).isEqualTo(Map.of("error", "Invalid credentials"));
+        login("1.2.3.4", "alice@x.test", "y");
+
+        ResponseEntity<?> blocked = login("1.2.3.4", "alice@x.test", "secret");
+        assertThat(blocked.getStatusCode()).isEqualTo(HttpStatus.TOO_MANY_REQUESTS);
+        assertThat(blocked.getHeaders().getFirst("Retry-After")).isEqualTo("900");
+        assertThat(blocked.getBody()).isEqualTo(Map.of("error", "Too many failed logins, try again in 15 min"));
+
+        assertThat(login("5.6.7.8", "alice@x.test", "secret").getStatusCode()).isEqualTo(HttpStatus.OK);
+    }
+
+    @Test
+    void blockedAttemptDoesNotCheckThePassword() {
+        for (int i = 0; i < 3; i++) {
+            login("1.2.3.4", "ghost@x.test", "x");
+        }
+        login("1.2.3.4", "alice@x.test", "secret");
+        verify(users, never()).checkPassword(any(), eq("secret"));
+    }
+}

backend/src/test/java/com/mailserver/controller/MailboxAdminControllerTest.java

@@ -0,0 +1,209 @@
+package com.mailserver.controller;
+
+import com.mailserver.config.MailAdmins;
+import com.mailserver.config.MailDomains;
+import com.mailserver.domain.User;
+import com.mailserver.service.MailService;
+import com.mailserver.service.UserService;
+import org.junit.jupiter.api.Test;
+import org.springframework.http.HttpStatus;
+import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
+import org.springframework.security.core.Authentication;
+import org.springframework.web.server.ResponseStatusException;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyLong;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+/** Settings → Mailboxes: only administrators; mailboxes only in our domains; a generated password comes back once. */
+class MailboxAdminControllerTest {
+
+    private final UserService users = mock(UserService.class);
+    private final MailService mail = mock(MailService.class);
+    private final MailDomains domains = new MailDomains("jambocheck.com", "");
+    private final MailAdmins admins = new MailAdmins("", "", domains);
+    private final com.mailserver.util.JwtUtils jwt = mock(com.mailserver.util.JwtUtils.class);
+    private final com.mailserver.service.MailLists lists = mock(com.mailserver.service.MailLists.class);
+    private final com.mailserver.service.MailboxAccess access = mock(com.mailserver.service.MailboxAccess.class);
+    private final com.mailserver.service.MailDirectory directory = new com.mailserver.service.MailDirectory(users, lists, domains, access);
+    private final MailboxAdminController controller = new MailboxAdminController(users, mail, domains, admins, jwt, directory, lists, access);
+
+    private final User admin = user(1L, "admin@jambocheck.com");
+    private final User alice = user(2L, "alice@jambocheck.com");
+
+    MailboxAdminControllerTest() {
+        when(mail.usedBytes(anyLong())).thenReturn(Mono.just(0L));
+        when(lists.exists(anyString())).thenReturn(Mono.just(false));
+        when(access.members(anyLong())).thenReturn(Flux.empty());
+        when(lists.exists("alerts@jambocheck.com")).thenReturn(Mono.just(true));
+        when(users.findOptional(anyString())).thenReturn(Mono.empty());
+        when(users.findOptional("alice@jambocheck.com")).thenReturn(Mono.just(alice));
+        when(lists.save(anyString(), any(), any(), any(Boolean.class), any())).thenAnswer(i ->
+                Mono.just(new com.mailserver.service.MailLists.MailList(5L, i.getArgument(0), i.getArgument(1), i.getArgument(2),
+                        i.getArgument(3), List.of("alice@jambocheck.com"))));
+        when(users.all()).thenReturn(Flux.just(alice, admin));
+        when(users.byId(1L)).thenReturn(Mono.just(admin));
+        when(users.byId(2L)).thenReturn(Mono.just(alice));
+        when(users.byId(99L)).thenReturn(Mono.empty());
+        when(users.register(anyString(), anyString(), any())).thenAnswer(i -> Mono.just(user(3L, i.getArgument(0))));
+        when(users.setPassword(any(), anyString())).thenAnswer(i -> Mono.just((User) i.getArgument(0)));
+        when(users.setActive(any(), any(Boolean.class))).thenAnswer(i -> {
+            User u = i.getArgument(0);
+            u.setActive(i.getArgument(1));
+            return Mono.just(u);
+        });
+        when(users.setTrap(any(), any(Boolean.class))).thenAnswer(i -> {
+            User u = i.getArgument(0);
+            u.setTrap(i.getArgument(1));
+            return Mono.just(u);
+        });
+    }
+
+    @Test
+    void mailboxAndListShareOneAddressSpaceNoPlusInNames() {
+        assertThat(status(() -> create("admin@jambocheck.com", "alerts@jambocheck.com", ""))).isEqualTo(HttpStatus.CONFLICT);
+        assertThat(status(() -> create("admin@jambocheck.com", "bob+x@jambocheck.com", ""))).isEqualTo(HttpStatus.BAD_REQUEST);
+        assertThat(create("admin@jambocheck.com", "jambotron_prod@jambocheck.com", "").mailbox().email()).isEqualTo("jambotron_prod@jambocheck.com");
+
+        var request = new MailboxAdminController.ListRequest("prod", "alerts", false, List.of("Alice@jambocheck.com"));
+        assertThat(controller.saveList(as("admin@jambocheck.com"), "alerts-prod@jambocheck.com", Mono.just(request)).block().members())
+                .containsExactly("alice@jambocheck.com");
+        assertThat(status(() -> controller.saveList(as("admin@jambocheck.com"), "alice@jambocheck.com", Mono.just(request)).block()))
+                .isEqualTo(HttpStatus.CONFLICT);
+        var unknown = new MailboxAdminController.ListRequest("prod", null, false, List.of("ghost@jambocheck.com"));
+        assertThat(status(() -> controller.saveList(as("admin@jambocheck.com"), "alerts-prod@jambocheck.com", Mono.just(unknown)).block()))
+                .isEqualTo(HttpStatus.BAD_REQUEST);
+        var badFolder = new MailboxAdminController.ListRequest("Trash", null, false, List.of());
+        assertThat(status(() -> controller.saveList(as("admin@jambocheck.com"), "alerts-prod@jambocheck.com", Mono.just(badFolder)).block()))
+                .isEqualTo(HttpStatus.BAD_REQUEST);
+        assertThat(status(() -> controller.saveList(as("alice@jambocheck.com"), "alerts-prod@jambocheck.com", Mono.just(request)).block()))
+                .isEqualTo(HttpStatus.FORBIDDEN);
+    }
+
+    @Test
+    void sharedMailboxHasNoPasswordShownMembersAreSet() {
+        when(users.setShared(any(), any(Boolean.class))).thenAnswer(i -> {
+            User u = i.getArgument(0);
+            u.setShared(i.getArgument(1));
+            return Mono.just(u);
+        });
+        var created = controller.create(as("admin@jambocheck.com"),
+                Mono.just(new MailboxAdminController.CreateRequest("support@jambocheck.com", "Support", "", true))).block();
+        assertThat(created.password()).isNull();
+        assertThat(created.mailbox().shared()).isTrue();
+
+        when(access.setMembers(anyLong(), any())).thenReturn(Mono.empty());
+        controller.members(as("admin@jambocheck.com"), 2L,
+                Mono.just(new MailboxAdminController.MembersRequest(List.of("Alice@jambocheck.com")))).block();
+        verify(access).setMembers(eq(2L), eq(List.of(2L)));
+        assertThat(status(() -> controller.members(as("admin@jambocheck.com"), 2L,
+                Mono.just(new MailboxAdminController.MembersRequest(List.of("ghost@jambocheck.com")))).block())).isEqualTo(HttpStatus.BAD_REQUEST);
+    }
+
+    @Test
+    void administratorSwitchesTrapOthersCanNot() {
+        assertThat(controller.trap(as("admin@jambocheck.com"), 2L, Mono.just(new MailboxAdminController.TrapRequest(true))).block().trap()).isTrue();
+        assertThat(alice.isTrap()).isTrue();
+        assertThat(controller.trap(as("admin@jambocheck.com"), 2L, Mono.just(new MailboxAdminController.TrapRequest(false))).block().trap()).isFalse();
+        assertThat(status(() -> controller.trap(as("alice@jambocheck.com"), 2L, Mono.just(new MailboxAdminController.TrapRequest(true))).block()))
+                .isEqualTo(HttpStatus.FORBIDDEN);
+    }
+
+    @Test
+    void administratorIsTheFirstMailboxByDefault() {
+        assertThat(admins.isAdmin("ADMIN@jambocheck.com")).isTrue();
+        assertThat(admins.isAdmin("alice@jambocheck.com")).isFalse();
+        assertThat(new MailAdmins("ops@jambocheck.com, root@jambocheck.com", "admin@jambocheck.com", domains).isAdmin("admin@jambocheck.com")).isFalse();
+    }
+
+    @Test
+    void listsMailboxesSortedForAnAdministratorOnly() {
+        List<MailboxAdminController.MailboxView> list = controller.list(as("admin@jambocheck.com")).collectList().block();
+        assertThat(list).extracting(MailboxAdminController.MailboxView::email).containsExactly("admin@jambocheck.com", "alice@jambocheck.com");
+        assertThat(list.get(0).admin()).isTrue();
+
+        assertThat(status(() -> controller.list(as("alice@jambocheck.com")).collectList().block())).isEqualTo(HttpStatus.FORBIDDEN);
+    }
+
+    @Test
+    void createsReservedNamesWithAGeneratedPasswordShownOnce() {
+        var created = controller.create(as("admin@jambocheck.com"),
+                Mono.just(new MailboxAdminController.CreateRequest(" No-Reply@JamboCheck.com ", "Jambotron", "", null))).block();
+
+        assertThat(created.mailbox().email()).isEqualTo("no-reply@jambocheck.com");
+        assertThat(created.password()).hasSizeGreaterThanOrEqualTo(20);
+        verify(users).register(eq("no-reply@jambocheck.com"), eq(created.password()), eq("Jambotron"));
+
+        var chosen = controller.create(as("admin@jambocheck.com"),
+                Mono.just(new MailboxAdminController.CreateRequest("monitor@jambocheck.com", null, "long-enough-1", null))).block();
+        assertThat(chosen.password()).isNull();
+    }
+
+    @Test
+    void refusesOtherDomainsBadAddressesShortPasswordsAndNonAdmins() {
+        assertThat(status(() -> create("admin@jambocheck.com", "x@gmail.com", ""))).isEqualTo(HttpStatus.BAD_REQUEST);
+        assertThat(status(() -> create("admin@jambocheck.com", "bad address@jambocheck.com", ""))).isEqualTo(HttpStatus.BAD_REQUEST);
+        assertThat(status(() -> create("admin@jambocheck.com", "x@jambocheck.com", "short"))).isEqualTo(HttpStatus.BAD_REQUEST);
+        assertThat(status(() -> create("alice@jambocheck.com", "x@jambocheck.com", ""))).isEqualTo(HttpStatus.FORBIDDEN);
+        verify(users, never()).register(anyString(), anyString(), any());
+
+        when(users.register(eq("alice@jambocheck.com"), anyString(), any())).thenReturn(Mono.error(new IllegalArgumentException("exists")));
+        assertThat(status(() -> create("admin@jambocheck.com", "alice@jambocheck.com", ""))).isEqualTo(HttpStatus.CONFLICT);
+    }
+
+    @Test
+    void newPasswordAndSwitchOffButNotYourself() {
+        var reset = controller.password(as("admin@jambocheck.com"), 2L, Mono.just(new MailboxAdminController.PasswordRequest(null))).block();
+        assertThat(reset.password()).isNotBlank();
+        verify(users).setPassword(alice, reset.password());
+
+        assertThat(controller.active(as("admin@jambocheck.com"), 2L, Mono.just(new MailboxAdminController.ActiveRequest(false))).block().active()).isFalse();
+        assertThat(status(() -> controller.active(as("admin@jambocheck.com"), 1L, Mono.just(new MailboxAdminController.ActiveRequest(false))).block()))
+                .isEqualTo(HttpStatus.BAD_REQUEST);
+    }
+
+    @Test
+    void administratorOpensAnyMailboxOthersCanNot() {
+        when(jwt.generateToken("alice@jambocheck.com", "admin@jambocheck.com")).thenReturn("alice-token");
+
+        var session = controller.open(as("admin@jambocheck.com"), 2L).block();
+        assertThat(session.getEmail()).isEqualTo("alice@jambocheck.com");
+        assertThat(session.getToken()).isEqualTo("alice-token");
+
+        assertThat(status(() -> controller.open(as("alice@jambocheck.com"), 1L).block())).isEqualTo(HttpStatus.FORBIDDEN);
+        assertThat(status(() -> controller.open(as("admin@jambocheck.com"), 99L).block())).isEqualTo(HttpStatus.NOT_FOUND);
+    }
+
+    private MailboxAdminController.Created create(String me, String email, String password) {
+        return controller.create(as(me), Mono.just(new MailboxAdminController.CreateRequest(email, null, password, null))).block();
+    }
+
+    private static Mono<Authentication> as(String email) {
+        return Mono.just(new UsernamePasswordAuthenticationToken(email, null, List.of()));
+    }
+
+    private static HttpStatus status(Runnable call) {
+        Throwable error = org.assertj.core.api.Assertions.catchThrowable(call::run);
+        assertThat(error).isInstanceOf(ResponseStatusException.class);
+        return HttpStatus.valueOf(((ResponseStatusException) error).getStatusCode().value());
+    }
+
+    private static User user(Long id, String email) {
+        User user = new User();
+        user.setId(id);
+        user.setEmail(email);
+        user.setPassword("hash");
+        return user;
+    }
+}

backend/src/test/java/com/mailserver/controller/ServiceControllerTest.java

@@ -0,0 +1,109 @@
+package com.mailserver.controller;
+
+import com.mailserver.config.MailDomains;
+import com.mailserver.domain.User;
+import com.mailserver.service.MailDirectory;
+import com.mailserver.service.MailLists;
+import com.mailserver.service.UserService;
+import org.junit.jupiter.api.Test;
+import org.springframework.http.HttpStatus;
+import org.springframework.web.server.ResponseStatusException;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.catchThrowable;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyLong;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+/** Service API for Jambotron: token only; account created once with a password; switched off → out of the lists. */
+class ServiceControllerTest {
+
+    private static final String AUTH = "Bearer s3cret-token";
+
+    private final UserService users = mock(UserService.class);
+    private final MailLists lists = mock(MailLists.class);
+    private final MailDomains domains = new MailDomains("jambocheck.com", "");
+    private final com.mailserver.service.MailboxAccess access = mock(com.mailserver.service.MailboxAccess.class);
+    private final MailDirectory directory = new MailDirectory(users, lists, domains, access);
+    private final User existing = user(7L, "jambotronpw@jambocheck.com");
+
+    ServiceControllerTest() {
+        when(users.findOptional(anyString())).thenReturn(Mono.empty());
+        when(users.findOptional("jambotronpw@jambocheck.com")).thenReturn(Mono.just(existing));
+        when(lists.exists(anyString())).thenReturn(Mono.just(false));
+        when(lists.listsOf(anyLong())).thenReturn(Flux.just("alerts-prod@jambocheck.com"));
+        when(lists.removeEverywhere(anyLong())).thenReturn(Mono.just(1L));
+        when(access.removeEverywhere(anyLong())).thenReturn(Mono.just(1L));
+        when(users.register(anyString(), anyString(), any())).thenAnswer(i -> Mono.just(user(8L, i.getArgument(0))));
+        when(users.setActive(any(), any(Boolean.class))).thenAnswer(i -> {
+            User u = i.getArgument(0);
+            u.setActive(i.getArgument(1));
+            return Mono.just(u);
+        });
+        when(users.setPassword(any(), anyString())).thenAnswer(i -> Mono.just((User) i.getArgument(0)));
+    }
+
+    private ServiceController api(String token) {
+        return new ServiceController(token, users, lists, directory, access);
+    }
+
+    @Test
+    void offWithoutTokenWrongTokenRefused() {
+        assertThat(status(() -> api("").account(AUTH, "jambotronpw@jambocheck.com"))).isEqualTo(HttpStatus.NOT_FOUND);
+        assertThat(status(() -> api("s3cret-token").account("Bearer nope", "jambotronpw@jambocheck.com"))).isEqualTo(HttpStatus.UNAUTHORIZED);
+        assertThat(status(() -> api("s3cret-token").account(null, "jambotronpw@jambocheck.com"))).isEqualTo(HttpStatus.UNAUTHORIZED);
+        assertThat(api("s3cret-token").account(AUTH, "jambotronpw@jambocheck.com").block().lists())
+                .containsExactly("alerts-prod@jambocheck.com");
+    }
+
+    @Test
+    void newAccountGetsPasswordOnceExistingDoesNot() {
+        var created = api("s3cret-token").saveAccount(AUTH, "moder@jambocheck.com",
+                Mono.just(new ServiceController.AccountRequest("Moder", true))).block();
+        assertThat(created.getStatusCode().value()).isEqualTo(201);
+        assertThat(created.getBody().password()).hasSizeGreaterThan(20);
+
+        var again = api("s3cret-token").saveAccount(AUTH, "jambotronpw@jambocheck.com",
+                Mono.just(new ServiceController.AccountRequest(null, null))).block();
+        assertThat(again.getStatusCode().value()).isEqualTo(200);
+        assertThat(again.getBody().password()).isNull();
+        verify(lists, never()).removeEverywhere(anyLong());
+
+        assertThat(status(() -> api("s3cret-token").saveAccount(AUTH, "x@gmail.com", Mono.empty()))).isEqualTo(HttpStatus.BAD_REQUEST);
+    }
+
+    @Test
+    void switchedOffLeavesEveryList() {
+        var off = api("s3cret-token").saveAccount(AUTH, "jambotronpw@jambocheck.com",
+                Mono.just(new ServiceController.AccountRequest(null, false))).block();
+        assertThat(off.getBody().account().active()).isFalse();
+        verify(lists).removeEverywhere(7L);
+        verify(access).removeEverywhere(7L);
+
+        var reset = api("s3cret-token").password(AUTH, "jambotronpw@jambocheck.com").block();
+        assertThat(reset.password()).isNotBlank();
+        verify(users).setPassword(existing, reset.password());
+    }
+
+    private static HttpStatus status(Runnable call) {
+        Throwable error = catchThrowable(call::run);
+        assertThat(error).isInstanceOf(ResponseStatusException.class);
+        return HttpStatus.valueOf(((ResponseStatusException) error).getStatusCode().value());
+    }
+
+    private static User user(Long id, String email) {
+        User user = new User();
+        user.setId(id);
+        user.setEmail(email);
+        user.setPassword("hash");
+        return user;
+    }
+}

backend/src/test/java/com/mailserver/imap/ImapServerTest.java

@@ -14,6 +14,7 @@ import jakarta.mail.internet.MimeMessage;
 import jakarta.mail.search.SubjectTerm;
 import org.eclipse.angus.mail.imap.AppendUID;
 import org.eclipse.angus.mail.imap.IMAPFolder;
+import com.mailserver.security.LoginGuard;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -184,6 +185,33 @@ class ImapServerTest {
         }
     }
 
+    @Test
+    void wrongPasswordsCloseTheConnectionAndTheGuardBlocksTheIp() throws Exception {
+        server.stop();
+        LoginGuard guard = new LoginGuard(new LoginGuard.Settings(true, 4, 100, Duration.ofMinutes(15),
+                Duration.ofMinutes(15), Duration.ofHours(24), Duration.ofDays(30), java.util.Set.of(), Duration.ZERO));
+        server = new ImapServer(new ImapServer.Settings("127.0.0.1", 0, "mx.example.test", false,
+                SmtpTls.serverContext(null, null, tlsDir, "mx.example.test"), false, 1_000_000,
+                Duration.ofMinutes(5), Duration.ofMillis(200)), store, guard);
+        server.start();
+        try (Client client = new Client(server.port())) {
+            client.read();
+            client.tls("s");
+            assertThat(client.send("a LOGIN alice@example.test w1")).startsWith("a NO [AUTHENTICATIONFAILED]");
+            assertThat(client.send("b LOGIN alice@example.test w2")).startsWith("b NO [AUTHENTICATIONFAILED]");
+            assertThat(client.untilTagged("c", "c LOGIN alice@example.test w3")).contains("* BYE Too many failed logins");
+            assertThat(client.read()).isNull();
+        }
+        try (Client client = new Client(server.port())) {
+            client.read();
+            client.tls("s");
+            assertThat(client.send("a LOGIN alice@example.test w4")).startsWith("a NO [AUTHENTICATIONFAILED]");
+            assertThat(client.untilTagged("b", "b LOGIN alice@example.test secret"))
+                    .anyMatch(line -> line.startsWith("* BYE Too many failed logins, try again in 15 min"))
+                    .anyMatch(line -> line.startsWith("b NO [UNAVAILABLE]"));
+        }
+    }
+
     @Test
     void loginIsRefusedInPlainTextAndTheGreetingSaysSo() throws Exception {
         try (Client client = new Client(server.port())) {

backend/src/test/java/com/mailserver/security/ActorTest.java

@@ -0,0 +1,24 @@
+package com.mailserver.security;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/** The login behind a session: own session, or a member who opened a shared mailbox. */
+class ActorTest {
+
+    @Test
+    void ownAndOpened() {
+        var own = new UsernamePasswordAuthenticationToken("bob@x", null, List.of());
+        assertThat(Actor.login(own)).isEqualTo("bob@x");
+        assertThat(Actor.opened(own)).isFalse();
+
+        var opened = new UsernamePasswordAuthenticationToken("support@x", null, List.of());
+        opened.setDetails("bob@x");
+        assertThat(Actor.login(opened)).isEqualTo("bob@x");
+        assertThat(Actor.opened(opened)).isTrue();
+    }
+}

backend/src/test/java/com/mailserver/security/LoginGuardTest.java

@@ -0,0 +1,164 @@
+package com.mailserver.security;
+
+import org.junit.jupiter.api.Test;
+
+import java.time.Clock;
+import java.time.Duration;
+import java.time.Instant;
+import java.time.ZoneOffset;
+import java.util.Set;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class LoginGuardTest {
+
+    /** Clock the test moves by hand. */
+    static final class TestClock extends Clock {
+        Instant now = Instant.parse("2026-11-06T12:00:00Z");
+
+        void plus(Duration d) {
+            now = now.plus(d);
+        }
+
+        @Override
+        public ZoneOffset getZone() {
+            return ZoneOffset.UTC;
+        }
+
+        @Override
+        public Clock withZone(java.time.ZoneId zone) {
+            return this;
+        }
+
+        @Override
+        public Instant instant() {
+            return now;
+        }
+    }
+
+    private final TestClock clock = new TestClock();
+
+    private LoginGuard guard(int perIp, int perAccount, String... trusted) {
+        return new LoginGuard(new LoginGuard.Settings(true, perIp, perAccount, Duration.ofMinutes(15),
+                Duration.ofMinutes(15), Duration.ofHours(24), Duration.ofDays(30), Set.of(trusted), Duration.ZERO), clock);
+    }
+
+    @Test
+    void ipIsBlockedAfterTheLimitWhateverMailboxItTries() {
+        LoginGuard guard = guard(3, 100);
+        for (int i = 0; i < 2; i++) {
+            guard.failure("1.2.3.4", "user" + i + "@x.test");
+        }
+        assertThat(guard.blocked("1.2.3.4", "any@x.test")).isFalse();
+        guard.failure("1.2.3.4", "user9@x.test");
+        assertThat(guard.retryAfter("1.2.3.4", "any@x.test")).isEqualTo(Duration.ofMinutes(15));
+        assertThat(guard.blocked("5.6.7.8", "any@x.test")).isFalse();
+
+        clock.plus(Duration.ofMinutes(15));
+        assertThat(guard.blocked("1.2.3.4", "any@x.test")).isFalse();
+    }
+
+    @Test
+    void failuresOutsideTheWindowDoNotCount() {
+        LoginGuard guard = guard(3, 100);
+        guard.failure("1.2.3.4", "a@x.test");
+        guard.failure("1.2.3.4", "a@x.test");
+        clock.plus(Duration.ofMinutes(16));
+        guard.failure("1.2.3.4", "a@x.test");
+        assertThat(guard.blocked("1.2.3.4", "a@x.test")).isFalse();
+    }
+
+    @Test
+    void eachNextBlockOfTheSameIpIsTwiceAsLongUpToTheMaximum() {
+        LoginGuard guard = guard(2, 100);
+        Duration expected = Duration.ofMinutes(15);
+        for (int round = 0; round < 10; round++) {
+            guard.failure("1.2.3.4", "a@x.test");
+            guard.failure("1.2.3.4", "a@x.test");
+            Duration wait = guard.retryAfter("1.2.3.4", "b@x.test");
+            assertThat(wait).isEqualTo(expected);
+            clock.plus(wait);
+            expected = expected.multipliedBy(2).compareTo(Duration.ofHours(24)) > 0 ? Duration.ofHours(24) : expected.multipliedBy(2);
+        }
+        // a quiet day forgives
+        clock.plus(Duration.ofHours(25));
+        guard.failure("1.2.3.4", "a@x.test");
+        guard.failure("1.2.3.4", "a@x.test");
+        assertThat(guard.retryAfter("1.2.3.4", "b@x.test")).isEqualTo(Duration.ofMinutes(15));
+    }
+
+    @Test
+    void attemptsWhileBlockedDoNotProlongTheBlock() {
+        LoginGuard guard = guard(2, 100);
+        guard.failure("1.2.3.4", "a@x.test");
+        guard.failure("1.2.3.4", "a@x.test");
+        clock.plus(Duration.ofMinutes(10));
+        guard.failure("1.2.3.4", "a@x.test");
+        assertThat(guard.retryAfter("1.2.3.4", "a@x.test")).isEqualTo(Duration.ofMinutes(5));
+    }
+
+    @Test
+    void distributedAttackBlocksTheMailboxButNotItsOwnerFromAKnownIp() {
+        LoginGuard guard = guard(100, 5);
+        guard.success("10.0.0.7", "Alice@X.test");
+        for (int i = 0; i < 5; i++) {
+            guard.failure("203.0.113." + i, "alice@x.test");
+        }
+        assertThat(guard.blocked("198.51.100.1", "alice@x.test")).isTrue();
+        assertThat(guard.blocked("198.51.100.1", "bob@x.test")).isFalse();
+        assertThat(guard.blocked("10.0.0.7", "alice@x.test")).isFalse();
+    }
+
+    @Test
+    void successForgivesTheIpFailuresButNotAnActiveBlock() {
+        LoginGuard guard = guard(3, 100);
+        guard.failure("1.2.3.4", "a@x.test");
+        guard.failure("1.2.3.4", "a@x.test");
+        guard.success("1.2.3.4", "a@x.test");
+        guard.failure("1.2.3.4", "a@x.test");
+        guard.failure("1.2.3.4", "a@x.test");
+        assertThat(guard.blocked("1.2.3.4", "a@x.test")).isFalse();
+        guard.failure("1.2.3.4", "a@x.test");
+        assertThat(guard.blocked("1.2.3.4", "a@x.test")).isTrue();
+        guard.success("1.2.3.4", "a@x.test");
+        assertThat(guard.blocked("1.2.3.4", "other@x.test")).isTrue();
+    }
+
+    @Test
+    void trustedIpIsNeverBlockedByIp() {
+        LoginGuard guard = guard(2, 100, "172.18.0.1");
+        for (int i = 0; i < 10; i++) {
+            guard.failure("172.18.0.1", "u" + i + "@x.test");
+        }
+        assertThat(guard.blocked("172.18.0.1", "new@x.test")).isFalse();
+    }
+
+    @Test
+    void sweepForgetsOldKeys() {
+        LoginGuard guard = guard(5, 5);
+        guard.failure("1.2.3.4", "a@x.test");
+        assertThat(guard.trackedIps()).isEqualTo(1);
+        assertThat(guard.trackedAccounts()).isEqualTo(1);
+        clock.plus(Duration.ofHours(25).plusMinutes(16));
+        guard.sweep();
+        assertThat(guard.trackedIps()).isZero();
+        assertThat(guard.trackedAccounts()).isZero();
+    }
+
+    @Test
+    void disabledGuardNeverBlocks() {
+        LoginGuard guard = LoginGuard.disabled();
+        for (int i = 0; i < 100; i++) {
+            guard.failure("1.2.3.4", "a@x.test");
+        }
+        assertThat(guard.blocked("1.2.3.4", "a@x.test")).isFalse();
+        assertThat(guard.failureDelay()).isZero();
+    }
+
+    @Test
+    void humanDuration() {
+        assertThat(LoginGuard.human(Duration.ofSeconds(30))).isEqualTo("1 min");
+        assertThat(LoginGuard.human(Duration.ofMinutes(15))).isEqualTo("15 min");
+        assertThat(LoginGuard.human(Duration.ofHours(4))).isEqualTo("4 h");
+    }
+}

backend/src/test/java/com/mailserver/service/DeliveryFolderTest.java

@@ -0,0 +1,21 @@
+package com.mailserver.service;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/** A "+tag" never puts mail into a system folder and never makes a strange folder name. */
+class DeliveryFolderTest {
+
+    @Test
+    void onlyPlainOwnFolderNames() {
+        assertThat(MailService.deliveryFolderName("prod")).isEqualTo("prod");
+        assertThat(MailService.deliveryFolderName("alerts.db-1")).isEqualTo("alerts.db-1");
+        assertThat(MailService.deliveryFolderName(null)).isNull();
+        assertThat(MailService.deliveryFolderName("inbox")).isNull();
+        assertThat(MailService.deliveryFolderName("Trash")).isNull();
+        assertThat(MailService.deliveryFolderName("spam")).isNull();
+        assertThat(MailService.deliveryFolderName("../x")).isNull();
+        assertThat(MailService.deliveryFolderName("a".repeat(51))).isNull();
+    }
+}

backend/src/test/java/com/mailserver/smtp/MailRouterTest.java

@@ -3,9 +3,11 @@ package com.mailserver.smtp;
 import com.mailserver.config.MailDomains;
 import com.mailserver.delivery.OutboundQueue;
 import com.mailserver.delivery.SmtpDeliveryClient;
+import com.mailserver.domain.User;
 import com.mailserver.repository.UserRepository;
 import com.mailserver.service.DkimService;
 import com.mailserver.service.LocalDelivery;
+import com.mailserver.service.MailLists;
 import com.mailserver.service.UserService;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Mono;
@@ -17,6 +19,7 @@ import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyBoolean;
 import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.ArgumentMatchers.isNull;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.verify;
@@ -29,13 +32,33 @@ class MailRouterTest {
     private final LocalDelivery localDelivery = mock(LocalDelivery.class);
     private final OutboundQueue queue = mock(OutboundQueue.class);
     private final SmtpDeliveryClient client = mock(SmtpDeliveryClient.class);
+    private final MailLists lists = mock(MailLists.class);
+
+    private SmtpDeliveryClient.Mode mode = SmtpDeliveryClient.Mode.OFF;
+
+    private static User user(String email, boolean trap) {
+        User user = new User();
+        user.setEmail(email);
+        user.setTrap(trap);
+        return user;
+    }
 
     private MailRouter router(String catchAll) {
         when(users.existsByEmail(anyString())).thenReturn(Mono.just(false));
         when(users.existsByEmail("bob@mail.test")).thenReturn(Mono.just(true));
-        when(client.mode()).thenReturn(SmtpDeliveryClient.Mode.OFF);
+        when(users.findByEmail(anyString())).thenReturn(Mono.empty());
+        when(users.findByEmail("bob@mail.test")).thenReturn(Mono.just(user("bob@mail.test", false)));
+        when(users.findByEmail("staging@mail.test")).thenReturn(Mono.just(user("staging@mail.test", true)));
+        when(users.existsByEmail("staging@mail.test")).thenReturn(Mono.just(true));
+        when(users.existsByEmail("ann@mail.test")).thenReturn(Mono.just(true));
+        when(client.mode()).thenReturn(mode);
+        when(lists.find(anyString())).thenReturn(Mono.empty());
+        when(lists.find("alerts-prod@mail.test")).thenReturn(Mono.just(new MailLists.MailList(1L, "alerts-prod@mail.test",
+                "prod", null, false, List.of("bob@mail.test", "ann@mail.test"))));
+        when(lists.find("talk@mail.test")).thenReturn(Mono.just(new MailLists.MailList(2L, "talk@mail.test",
+                null, null, true, List.of("bob@mail.test"))));
         return new MailRouter(new MailDomains("mail.test", catchAll), users, mock(UserService.class), localDelivery,
-                queue, mock(DkimService.class), client);
+                queue, mock(DkimService.class), client, lists, mock(com.mailserver.service.MailboxAccess.class));
     }
 
     @Test
@@ -61,8 +84,70 @@ class MailRouterTest {
                 new SmtpBackend.Recipient("user@gmail.com", SmtpBackend.Route.LOCAL),
                 new SmtpBackend.Recipient("bob@mail.test", SmtpBackend.Route.LOCAL))), "Subject: hi\r\n\r\nbody".getBytes());
 
-        verify(localDelivery).deliver(any(), eq("trap@mail.test"), eq("10.0.0.5"), eq("no-reply@jambotron.com"), anyBoolean());
+        verify(localDelivery).deliver(any(), eq("trap@mail.test"), isNull(), eq("10.0.0.5"), eq("no-reply@jambotron.com"), anyBoolean());
-        verify(localDelivery).deliver(any(), eq("bob@mail.test"), eq("10.0.0.5"), eq("no-reply@jambotron.com"), anyBoolean());
+        verify(localDelivery).deliver(any(), eq("bob@mail.test"), isNull(), eq("10.0.0.5"), eq("no-reply@jambotron.com"), anyBoolean());
         verify(queue, never()).enqueue(any(), any(), any());
     }
+
+    @Test
+    void trapMailboxKeepsOutsideMailButOurAddressesStillGetIt() throws Exception {
+        mode = SmtpDeliveryClient.Mode.MX;
+        MailRouter router = router("");
+
+        // an ordinary mailbox still sends outside; the trap one keeps outside mail, ours is delivered
+        assertThat(router.route("user@gmail.com", "bob@mail.test")).isEqualTo(SmtpBackend.Route.OUTBOUND);
+        assertThat(router.route("user@gmail.com", "staging@mail.test")).isEqualTo(SmtpBackend.Route.TRAP);
+        assertThat(router.route("user@gmail.com", "Staging@Mail.test")).isEqualTo(SmtpBackend.Route.TRAP);
+        assertThat(router.route("nobody@mail.test", "staging@mail.test")).isEqualTo(SmtpBackend.Route.TRAP);
+        assertThat(router.route("bob@mail.test", "staging@mail.test")).isEqualTo(SmtpBackend.Route.LOCAL);
+        assertThat(router.route("alerts-prod@mail.test", "staging@mail.test")).isEqualTo(SmtpBackend.Route.LOCAL);
+
+        router.accept(new SmtpBackend.Envelope("10.0.0.5", "staging", "staging@mail.test", "staging@mail.test", List.of(
+                new SmtpBackend.Recipient("user@gmail.com", SmtpBackend.Route.TRAP),
+                new SmtpBackend.Recipient("other@yahoo.com", SmtpBackend.Route.TRAP),
+                new SmtpBackend.Recipient("bob@mail.test", SmtpBackend.Route.LOCAL))), "Subject: hi\r\n\r\nbody".getBytes());
+
+        verify(localDelivery).deliver(any(), eq("staging@mail.test"), isNull(), eq("10.0.0.5"), eq("staging@mail.test"), eq(true));
+        verify(localDelivery).deliver(any(), eq("bob@mail.test"), isNull(), eq("10.0.0.5"), eq("staging@mail.test"), eq(true));
+        verify(queue, never()).enqueue(any(), any(), any());
+    }
+
+    @Test
+    void plusTagGoesToThatFolderOfTheMailbox() throws Exception {
+        MailRouter router = router("");
+
+        assertThat(router.route("bob+prod@mail.test", null)).isEqualTo(SmtpBackend.Route.LOCAL);
+        assertThat(router.route("nobody+prod@mail.test", null)).isEqualTo(SmtpBackend.Route.UNKNOWN_USER);
+
+        router.accept(new SmtpBackend.Envelope("10.0.0.5", "x", "a@b.c", null, List.of(
+                new SmtpBackend.Recipient("Bob+Prod@mail.test", SmtpBackend.Route.LOCAL))), "Subject: hi\r\n\r\nbody".getBytes());
+
+        verify(localDelivery).deliver(any(), eq("bob@mail.test"), eq("Prod"), eq("10.0.0.5"), eq("a@b.c"), eq(false));
+    }
+
+    @Test
+    void listGivesEveryMemberOwnCopyInTheListFolderClosedListOnlyForLoggedIn() throws Exception {
+        MailRouter router = router("");
+
+        assertThat(router.route("alerts-prod@mail.test", null)).isEqualTo(SmtpBackend.Route.LIST_CLOSED);
+        assertThat(router.route("alerts-prod@mail.test", "monitor@mail.test")).isEqualTo(SmtpBackend.Route.LOCAL);
+        assertThat(router.route("talk@mail.test", null)).isEqualTo(SmtpBackend.Route.LOCAL);
+
+        // list + one member directly: the member gets the list copy AND the direct one (different folders), once each
+        router.accept(new SmtpBackend.Envelope("10.0.0.5", "kuma", "monitor@mail.test", "monitor@mail.test", List.of(
+                new SmtpBackend.Recipient("alerts-prod@mail.test", SmtpBackend.Route.LOCAL),
+                new SmtpBackend.Recipient("ALERTS-PROD@mail.test", SmtpBackend.Route.LOCAL),
+                new SmtpBackend.Recipient("bob@mail.test", SmtpBackend.Route.LOCAL))), "Subject: down\r\n\r\nbody".getBytes());
+
+        verify(localDelivery).deliver(any(), eq("bob@mail.test"), eq("prod"), any(), any(), eq(true));
+        verify(localDelivery).deliver(any(), eq("ann@mail.test"), eq("prod"), any(), any(), eq(true));
+        verify(localDelivery).deliver(any(), eq("bob@mail.test"), isNull(), any(), any(), eq(true));
+    }
+
+    @Test
+    void listTagOverridesTheListFolder() {
+        MailRouter router = router("");
+        assertThat(router.targets("alerts-prod+db@mail.test")).containsExactly(
+                new MailRouter.Target("bob@mail.test", "db"), new MailRouter.Target("ann@mail.test", "db"));
+    }
 }

backend/src/test/java/com/mailserver/smtp/ReloadingKeyManagerTest.java

@@ -0,0 +1,149 @@
+package com.mailserver.smtp;
+
+import org.bouncycastle.asn1.x500.X500Name;
+import org.bouncycastle.cert.jcajce.JcaX509CertificateConverter;
+import org.bouncycastle.cert.jcajce.JcaX509v3CertificateBuilder;
+import org.bouncycastle.openssl.jcajce.JcaPEMWriter;
+import org.bouncycastle.operator.jcajce.JcaContentSignerBuilder;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+import java.io.StringWriter;
+import java.math.BigInteger;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.attribute.FileTime;
+import java.security.KeyPair;
+import java.security.KeyPairGenerator;
+import java.security.cert.X509Certificate;
+import java.time.Clock;
+import java.time.Duration;
+import java.time.Instant;
+import java.time.ZoneOffset;
+import java.util.Date;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class ReloadingKeyManagerTest {
+
+    /** A clock moved by hand */
+    static final class TestClock extends Clock {
+        Instant now = Instant.parse("2026-11-06T12:00:00Z");
+
+        @Override
+        public ZoneOffset getZone() {
+            return ZoneOffset.UTC;
+        }
+
+        @Override
+        public Clock withZone(java.time.ZoneId zone) {
+            return this;
+        }
+
+        @Override
+        public Instant instant() {
+            return now;
+        }
+    }
+
+    @Test
+    void readsTheFilesAgainWhenTheyChange(@TempDir Path dir) throws Exception {
+        Path cert = dir.resolve("cert.pem");
+        Path key = dir.resolve("key.pem");
+        SmtpTls.selfSigned("old.example", cert, key);
+        TestClock clock = new TestClock();
+        ReloadingKeyManager manager = new ReloadingKeyManager(cert, key, Duration.ofMinutes(1), clock);
+
+        String first = manager.chooseEngineServerAlias("RSA", null, null);
+        assertEquals("CN=old.example", subject(manager.getCertificateChain(first)));
+        assertNull(manager.chooseEngineServerAlias("EC", null, null), "an RSA key is not offered for EC");
+
+        SmtpTls.selfSigned("new.example", cert, key);
+        Files.setLastModifiedTime(cert, FileTime.from(Instant.now().plusSeconds(5)));
+        Files.setLastModifiedTime(key, FileTime.from(Instant.now().plusSeconds(5)));
+
+        assertEquals(first, manager.chooseEngineServerAlias("RSA", null, null), "not checked before the interval");
+
+        clock.now = clock.now.plus(Duration.ofMinutes(1));
+        String second = manager.chooseEngineServerAlias("RSA", null, null);
+        assertNotEquals(first, second);
+        assertEquals("CN=new.example", subject(manager.getCertificateChain(second)));
+        assertNotNull(manager.getPrivateKey(second));
+        assertNotNull(manager.getCertificateChain(first), "a handshake that holds the previous alias still finishes");
+    }
+
+    @Test
+    void keepsTheOldCertificateWhenTheNewFileIsBroken(@TempDir Path dir) throws Exception {
+        Path cert = dir.resolve("cert.pem");
+        Path key = dir.resolve("key.pem");
+        SmtpTls.selfSigned("old.example", cert, key);
+        TestClock clock = new TestClock();
+        ReloadingKeyManager manager = new ReloadingKeyManager(cert, key, Duration.ofMinutes(1), clock);
+
+        Files.writeString(cert, "-----BEGIN CERTIFICATE-----\nhalf");
+        Files.setLastModifiedTime(cert, FileTime.from(Instant.now().plusSeconds(5)));
+        clock.now = clock.now.plus(Duration.ofMinutes(2));
+
+        String alias = manager.chooseEngineServerAlias("RSA", null, null);
+        assertEquals("CN=old.example", subject(manager.getCertificateChain(alias)));
+    }
+
+    @Test
+    void readsTraditionalEcKeysAsLegoWritesThem(@TempDir Path dir) throws Exception {
+        KeyPairGenerator generator = KeyPairGenerator.getInstance("EC");
+        generator.initialize(256);
+        KeyPair pair = generator.generateKeyPair();
+        X500Name name = new X500Name("CN=mail.example");
+        X509Certificate certificate = new JcaX509CertificateConverter().getCertificate(
+                new JcaX509v3CertificateBuilder(name, BigInteger.ONE, new Date(System.currentTimeMillis() - 86_400_000L),
+                        new Date(System.currentTimeMillis() + 86_400_000L), name, pair.getPublic())
+                        .build(new JcaContentSignerBuilder("SHA256withECDSA").build(pair.getPrivate())));
+        Path cert = dir.resolve("cert.pem");
+        Path key = dir.resolve("key.pem");
+        Files.writeString(cert, pem(certificate));
+        Files.writeString(key, sec1(pair)); // -----BEGIN EC PRIVATE KEY----- (SEC1 with the curve), not PKCS#8
+        assertTrue(Files.readString(key).contains("EC PRIVATE KEY"));
+
+        ReloadingKeyManager manager = new ReloadingKeyManager(cert, key, Duration.ofMinutes(1), new TestClock());
+        String alias = manager.chooseEngineServerAlias("EC", null, null);
+        assertNotNull(alias);
+        assertEquals("EC", manager.getPrivateKey(alias).getAlgorithm());
+        assertNull(manager.chooseEngineServerAlias("RSA", null, null));
+    }
+
+    @Test
+    void refusesAKeyThatDoesNotMatchTheCertificateType(@TempDir Path dir) throws Exception {
+        Path cert = dir.resolve("cert.pem");
+        Path key = dir.resolve("key.pem");
+        SmtpTls.selfSigned("rsa.example", cert, key);
+        KeyPairGenerator generator = KeyPairGenerator.getInstance("EC");
+        generator.initialize(256);
+        Files.writeString(key, sec1(generator.generateKeyPair()));
+        assertThrows(IllegalStateException.class,
+                () -> new ReloadingKeyManager(cert, key, Duration.ofMinutes(1), new TestClock()));
+    }
+
+    /** As lego and openssl ecparam -genkey write it: SEC1 with the named curve secp256r1 */
+    private static String sec1(KeyPair pair) throws Exception {
+        java.security.interfaces.ECPrivateKey key = (java.security.interfaces.ECPrivateKey) pair.getPrivate();
+        org.bouncycastle.asn1.sec.ECPrivateKey sec1 = new org.bouncycastle.asn1.sec.ECPrivateKey(256, key.getS(),
+                new org.bouncycastle.asn1.x9.X962Parameters(org.bouncycastle.asn1.sec.SECObjectIdentifiers.secp256r1));
+        StringWriter out = new StringWriter();
+        try (org.bouncycastle.util.io.pem.PemWriter writer = new org.bouncycastle.util.io.pem.PemWriter(out)) {
+            writer.writeObject(new org.bouncycastle.util.io.pem.PemObject("EC PRIVATE KEY", sec1.getEncoded()));
+        }
+        return out.toString();
+    }
+
+    private static String subject(X509Certificate[] chain) {
+        return chain[0].getSubjectX500Principal().getName();
+    }
+
+    private static String pem(Object object) throws Exception {
+        StringWriter out = new StringWriter();
+        try (JcaPEMWriter writer = new JcaPEMWriter(out)) {
+            writer.writeObject(object);
+        }
+        return out.toString();
+    }
+}

backend/src/test/java/com/mailserver/smtp/SmtpServerTest.java

@@ -5,6 +5,7 @@ import jakarta.mail.Session;
 import jakarta.mail.Transport;
 import jakarta.mail.internet.InternetAddress;
 import jakarta.mail.internet.MimeMessage;
+import com.mailserver.security.LoginGuard;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -42,8 +43,8 @@ class SmtpServerTest {
         volatile boolean failStore;
 
         @Override
-        public boolean authenticate(String username, String password) {
+        public String authenticate(String username, String password) {
-            return password.equals(passwords.get(username));
+            return password.equals(passwords.get(username)) ? username : null;
         }
 
         @Override
@@ -158,6 +159,34 @@ class SmtpServerTest {
         assertThat(backend.messages.get(0)).contains("with ESMTPA;");
     }
 
+    @Test
+    void threeWrongPasswordsCloseTheConnectionAndTheGuardBlocksTheIp() throws Exception {
+        server.stop();
+        LoginGuard guard = new LoginGuard(new LoginGuard.Settings(true, 4, 100, Duration.ofMinutes(15),
+                Duration.ofMinutes(15), Duration.ofHours(24), Duration.ofDays(30), java.util.Set.of(), Duration.ZERO));
+        server = new SmtpServer(new SmtpServer.Settings("127.0.0.1", 0, "mx.example.test", 2000, true,
+                Duration.ofSeconds(30)), backend, guard);
+        server.start();
+        try (Client client = new Client(server.port())) {
+            client.read();
+            client.send("EHLO laptop");
+            client.readReplyLines();
+            assertThat(client.send("AUTH PLAIN " + b64("\0alice@example.test\0w1"))).startsWith("535");
+            assertThat(client.send("AUTH PLAIN " + b64("\0alice@example.test\0w2"))).startsWith("535");
+            assertThat(client.send("AUTH PLAIN " + b64("\0alice@example.test\0w3"))).startsWith("535").contains("closing");
+            assertThat(client.read()).isNull();
+        }
+        try (Client client = new Client(server.port())) {
+            client.read();
+            client.send("EHLO laptop");
+            client.readReplyLines();
+            assertThat(client.send("AUTH PLAIN " + b64("\0bob@example.test\0w4"))).startsWith("535");
+            // 4th failure from 127.0.0.1: blocked — even the right password is not checked
+            assertThat(client.send("AUTH PLAIN " + b64("\0alice@example.test\0secret"))).startsWith("421 4.7.0");
+            assertThat(client.read()).isNull();
+        }
+    }
+
     @Test
     void authLoginWorksToo() throws Exception {
         try (Client client = new Client(server.port())) {

docker-compose.image.yml

@@ -19,11 +19,11 @@ services:
       - -c
       - |
         umask 077
-        for name in DB_PASSWORD JWT_SECRET; do
+        for name in DB_PASSWORD JWT_SECRET SERVICE_TOKEN; do
           [ -s /secrets/$$name ] || head -c 48 /dev/urandom | base64 | tr -dc 'A-Za-z0-9' > /secrets/$$name
         done
         # postgres reads it as uid 70, the app as uid 10001 — readable inside these containers only
-        chmod 644 /secrets/DB_PASSWORD /secrets/JWT_SECRET
+        chmod 644 /secrets/DB_PASSWORD /secrets/JWT_SECRET /secrets/SERVICE_TOKEN
     volumes:
       - secrets:/secrets
 

docker-compose.jambotron.yml

@@ -16,11 +16,11 @@ services:
       - -c
       - |
         umask 077
-        for name in DB_PASSWORD JWT_SECRET; do
+        for name in DB_PASSWORD JWT_SECRET SERVICE_TOKEN; do
           [ -s /secrets/$$name ] || head -c 48 /dev/urandom | base64 | tr -dc 'A-Za-z0-9' > /secrets/$$name
         done
         # postgres reads it as uid 70, the app as uid 10001 — readable inside these containers only
-        chmod 644 /secrets/DB_PASSWORD /secrets/JWT_SECRET
+        chmod 644 /secrets/DB_PASSWORD /secrets/JWT_SECRET /secrets/SERVICE_TOKEN
     volumes:
       - secrets:/secrets
 

docker-compose.public.yml

@@ -0,0 +1,159 @@
+# Real mail on the internet (v0.2.3 75.6): receives mail for MAIL_DOMAINS and sends it straight to the recipients'
+# MX servers (port 25), DKIM-signed. From the ready image, like docker-compose.image.yml.
+#
+# Needs a VM of its own with a public address (Jambotron 60.8: «Публичный адрес» of the VM, SMTP «да» — port 25
+# is closed by default) — the ports below are published on that address:
+#   25   SMTP: mail from other servers (STARTTLS) and from mail programs
+#   587  submission: mail programs (STARTTLS + login) — the same SMTP listener as 25
+#   465  SMTPS: mail programs, implicit TLS
+#   993  IMAPS: mail programs, implicit TLS
+#   80   only for Let's Encrypt (HTTP-01) — service "acme"
+#   443  web client + API over HTTPS, same Let's Encrypt certificate (acme): https://mail.jambocheck.com
+# The web client + API can also go through Jambotron's Caddy (plain port 8080) under ANOTHER name
+# (webmail.<domain>): the name MAIL_HOSTNAME points at the VM's public address, not at Caddy.
+#
+# DNS before the first start (the certificate is issued over HTTP on MAIL_HOSTNAME):
+#   A    mail.<domain>             → public address of the VM
+#   PTR  public address            → mail.<domain>        (hoster's panel: Reverse DNS)
+#   MX   <domain>                  → 10 mail.<domain>
+#   TXT  <domain>                  → "v=spf1 ip4:<public address> -all"
+#   TXT  _dmarc.<domain>           → "v=DMARC1; p=none; rua=mailto:postmaster@<domain>"
+#   TXT  mail._domainkey.<domain>  → printed in the "mail" log on the first start (DKIM key, kept in the data volume)
+#
+# Mailbox admin@<domain>: its password is in the "mail" log on the first start and in /app/data/initial-passwords.txt.
+# Registration is closed: new mailboxes only by the admin. No catch-all.
+# Defaults are ours (mail.jambocheck.com / jambocheck.com) — Jambotron deploys without a .env; another domain:
+# MAIL_HOSTNAME, MAIL_DOMAINS, ACME_EMAIL in .env next to this file.
+name: reactive-mail-public
+
+services:
+  secrets-init:
+    image: alpine:3.20
+    restart: "no"
+    command:
+      - sh
+      - -c
+      - |
+        umask 077
+        for name in DB_PASSWORD JWT_SECRET SERVICE_TOKEN; do
+          [ -s /secrets/$$name ] || head -c 48 /dev/urandom | base64 | tr -dc 'A-Za-z0-9' > /secrets/$$name
+        done
+        chmod 644 /secrets/DB_PASSWORD /secrets/JWT_SECRET /secrets/SERVICE_TOKEN
+    volumes:
+      - secrets:/secrets
+
+  # Let's Encrypt for MAIL_HOSTNAME: issued on the first start, renewed 30 days before the end (checked twice a day).
+  # The deploy hook copies the pair to /tls (readable by the "mail" user 10001); the server reads it again within
+  # a minute — no restart
+  acme:
+    image: goacme/lego:v5.5.2
+    restart: unless-stopped
+    ports:
+      - "80:80"
+    entrypoint:
+      - sh
+      - -c
+      - |
+        cat > /usr/local/bin/jb-deploy <<'EOF'
+        #!/bin/sh
+        set -e
+        cp "$$LEGO_HOOK_CERT_PATH" /tls/cert.pem.new
+        cp "$$LEGO_HOOK_CERT_KEY_PATH" /tls/key.pem.new
+        chown 10001 /tls/cert.pem.new /tls/key.pem.new
+        chmod 600 /tls/key.pem.new
+        chmod 644 /tls/cert.pem.new
+        mv /tls/key.pem.new /tls/key.pem
+        mv /tls/cert.pem.new /tls/cert.pem
+        echo "certificate for $$LEGO_HOOK_CERT_DOMAINS copied to /tls"
+        EOF
+        chmod 755 /usr/local/bin/jb-deploy
+        while true; do
+          /lego run --accept-tos --email "$$ACME_EMAIL" --domains "$$MAIL_HOSTNAME" --key-type EC256 \
+            --http --http.address :80 --path /var/lib/lego --renew-days 30 --no-random-sleep \
+            --deploy-hook /usr/local/bin/jb-deploy || echo "lego failed — next try in 1 hour"
+          [ -s /tls/cert.pem ] && sleep 43200 || sleep 3600
+        done
+    environment:
+      MAIL_HOSTNAME: ${MAIL_HOSTNAME:-mail.jambocheck.com}
+      ACME_EMAIL: ${ACME_EMAIL:-postmaster@jambocheck.com}
+      LEGO_LOG_FORMAT: text
+    volumes:
+      - lego:/var/lib/lego
+      - tls:/tls
+    healthcheck:
+      test: ["CMD-SHELL", "test -s /tls/cert.pem && test -s /tls/key.pem"]
+      interval: 15s
+      timeout: 5s
+      start_period: 10m
+      retries: 3
+    mem_limit: 128m
+
+  db:
+    image: postgres:17
+    restart: unless-stopped
+    depends_on:
+      secrets-init:
+        condition: service_completed_successfully
+    environment:
+      POSTGRES_DB: mailserver
+      POSTGRES_USER: mail
+      POSTGRES_PASSWORD_FILE: /run/mail-secrets/DB_PASSWORD
+    volumes:
+      - pgdata:/var/lib/postgresql/data
+      - secrets:/run/mail-secrets:ro
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U mail -d mailserver"]
+      interval: 10s
+      timeout: 5s
+      retries: 10
+    mem_limit: 256m
+
+  mail:
+    image: gitea.jambotron.com/jambotron_gang/reactive-mail-server:${MAIL_IMAGE_TAG:-latest}
+    pull_policy: always
+    restart: unless-stopped
+    depends_on:
+      db:
+        condition: service_healthy
+      acme:
+        condition: service_healthy   # waits for the first certificate
+    ports:
+      - "25:3025"
+      - "587:3025"
+      - "465:3465"
+      - "993:3993"
+      - "443:8443"   # web client + API over HTTPS: https://mail.jambocheck.com
+    expose:
+      - "8080"   # plain HTTP, for a reverse proxy inside the network (not needed on the public address)
+    environment:
+      DB_HOST: db
+      MAILSERVER_SECRETS_DIR: /run/mail-secrets
+      MAIL_DOMAINS: ${MAIL_DOMAINS:-jambocheck.com}
+      MAIL_HOSTNAME: ${MAIL_HOSTNAME:-mail.jambocheck.com}
+      MAIL_TLS_CERT: /tls/cert.pem
+      MAIL_TLS_KEY: /tls/key.pem
+      SMTPS_PORT: "3465"
+      IMAPS_PORT: "3993"
+      HTTPS_PORT: "8443"
+      DKIM_DOMAIN: ${MAIL_DOMAINS:-jambocheck.com}
+      DKIM_SELECTOR: mail
+      DKIM_KEYS_DIR: /app/data/dkim-keys
+      MAIL_CATCH_ALL: ""
+      MAIL_REGISTRATION: "false"
+      OUTBOUND_MODE: mx
+      SMTP_AUTH_WITHOUT_TLS: "false"
+      IMAP_AUTH_WITHOUT_TLS: "false"
+      SPF_ENABLED: "true"
+      DMARC_ENABLED: "true"
+    volumes:
+      - data:/app/data
+      - secrets:/run/mail-secrets:ro
+      - tls:/tls:ro
+    mem_limit: 512m
+
+volumes:
+  secrets:
+  pgdata:
+  data:
+  lego:
+  tls:

frontend/src/app/core/api.service.ts

@@ -1,7 +1,7 @@
 import { Injectable, inject } from '@angular/core';
 import { HttpClient } from '@angular/common/http';
 import { Observable } from 'rxjs';
-import { Attachment, BlacklistEntry, Contact, Draft, Folder, Message, Profile, ServerConfig } from './models';
+import { Attachment, BlacklistEntry, Contact, Draft, Folder, MailList, Mailbox, MailboxCreated, MailboxEntry, Message, Profile, ServerConfig } from './models';
 
 /** The mail server REST API (same origin, /api). */
 @Injectable({ providedIn: 'root' })
@@ -17,6 +17,45 @@ export class ApiService {
     return this.http.put('/api/me/password', { currentPassword, newPassword });
   }
 
+  // mailboxes — administrators only
+  mailboxes(): Observable<Mailbox[]> { return this.http.get<Mailbox[]>('/api/admin/mailboxes'); }
+  createMailbox(email: string, displayName: string, password: string, shared = false): Observable<MailboxCreated> {
+    return this.http.post<MailboxCreated>('/api/admin/mailboxes', { email, displayName, password, shared });
+  }
+  setMailboxMembers(id: number, members: string[]): Observable<Mailbox> {
+    return this.http.put<Mailbox>(`/api/admin/mailboxes/${id}/members`, { members });
+  }
+  // the logged-in user's mailboxes (left menu)
+  myMailboxes(): Observable<MailboxEntry[]> { return this.http.get<MailboxEntry[]>('/api/mailboxes'); }
+  mailboxSession(email: string): Observable<{ token: string; email: string }> {
+    return this.http.post<{ token: string; email: string }>(`/api/mailboxes/${encodeURIComponent(email)}/session`, {});
+  }
+  attachMailbox(email: string, password: string): Observable<MailboxEntry> {
+    return this.http.post<MailboxEntry>('/api/mailboxes/attach', { email, password });
+  }
+  leaveMailbox(email: string): Observable<void> {
+    return this.http.delete<void>(`/api/mailboxes/${encodeURIComponent(email)}`);
+  }
+  newMailboxPassword(id: number): Observable<MailboxCreated> {
+    return this.http.post<MailboxCreated>(`/api/admin/mailboxes/${id}/password`, {});
+  }
+  openMailbox(id: number): Observable<{ token: string; email: string }> {
+    return this.http.post<{ token: string; email: string }>(`/api/admin/mailboxes/${id}/open`, {});
+  }
+  mailLists(): Observable<MailList[]> { return this.http.get<MailList[]>('/api/admin/mailboxes/lists'); }
+  saveMailList(address: string, list: { folder: string; description: string; openToOutside: boolean; members: string[] }): Observable<MailList> {
+    return this.http.put<MailList>(`/api/admin/mailboxes/lists/${encodeURIComponent(address)}`, list);
+  }
+  deleteMailList(address: string): Observable<void> {
+    return this.http.delete<void>(`/api/admin/mailboxes/lists/${encodeURIComponent(address)}`);
+  }
+  setMailboxTrap(id: number, trap: boolean): Observable<Mailbox> {
+    return this.http.put<Mailbox>(`/api/admin/mailboxes/${id}/trap`, { trap });
+  }
+  setMailboxActive(id: number, active: boolean): Observable<Mailbox> {
+    return this.http.put<Mailbox>(`/api/admin/mailboxes/${id}/active`, { active });
+  }
+
   // folders
   folders(): Observable<Folder[]> { return this.http.get<Folder[]>('/api/folders'); }
   createFolder(name: string): Observable<Folder> { return this.http.post<Folder>('/api/folders', { name }); }
@@ -42,8 +81,8 @@ export class ApiService {
   // compose
   createDraft(draft: Draft): Observable<Message> { return this.http.post<Message>('/api/drafts', draft); }
   updateDraft(id: number, draft: Draft): Observable<Message> { return this.http.put<Message>(`/api/drafts/${id}`, draft); }
-  send(draft: Draft, draftId: number | null): Observable<Message> {
+  send(draft: Draft, draftId: number | null, replyToId: number | null = null): Observable<Message> {
-    return this.http.post<Message>('/api/send', { ...draft, draftId });
+    return this.http.post<Message>('/api/send', { ...draft, draftId, replyToId });
   }
 
   // attachments

frontend/src/app/core/auth.service.ts

@@ -12,6 +12,8 @@ export class AuthService {
   private router = inject(Router);
 
   readonly email = signal<string | null>(read('email'));
+  /** Administrator who opened this mailbox (Settings → MAILBOXES → Open), or null */
+  readonly openedBy = signal<string | null>(read('adminEmail'));
   readonly loggedIn = computed(() => this.email() !== null && read('token') !== null);
 
   login(email: string, password: string): Observable<TokenResponse> {
@@ -24,6 +26,44 @@ export class AuthService {
 
   token(): string | null { return read('token'); }
 
+  /** Administrator opens another mailbox: its session, the admin session kept to come back. */
+  openAs(response: TokenResponse): void {
+    const adminToken = read('token');
+    const adminEmail = read('email');
+    try {
+      if (adminToken && adminEmail && !read('adminToken')) {
+        localStorage.setItem('adminToken', adminToken);
+        localStorage.setItem('adminEmail', adminEmail);
+      }
+    } catch { /* storage blocked */ }
+    this.store(response);
+    this.openedBy.set(read('adminEmail'));
+  }
+
+  /**
+   * Switch to another mailbox of the same login (left menu). Going back to the mailbox an administrator came
+   * from ends the administrator's visit.
+   */
+  switchTo(response: TokenResponse): void {
+    if (this.openedBy() && response.email === this.openedBy()) {
+      this.backToAdmin();
+      return;
+    }
+    this.store(response);
+  }
+
+  /** Back to the administrator's own mailbox. */
+  backToAdmin(): void {
+    const token = read('adminToken');
+    const email = read('adminEmail');
+    try {
+      localStorage.removeItem('adminToken');
+      localStorage.removeItem('adminEmail');
+    } catch { /* storage blocked */ }
+    this.openedBy.set(null);
+    if (token && email) { this.store({ token, email }); } else { this.clear(); }
+  }
+
   logout(): void {
     this.clear();
     this.router.navigate(['/login']);
@@ -33,8 +73,11 @@ export class AuthService {
     try {
       localStorage.removeItem('token');
       localStorage.removeItem('email');
+      localStorage.removeItem('adminToken');
+      localStorage.removeItem('adminEmail');
     } catch { /* storage blocked */ }
     this.email.set(null);
+    this.openedBy.set(null);
   }
 
   private store(response: TokenResponse): void {

frontend/src/app/core/models.ts

@@ -23,6 +23,16 @@ export interface Message {
   receivedAt: string;
   hasAttachments: boolean;
   attachmentCount: number;
+  answeredBy?: string | null;   // login that answered it from the web client (shared mailboxes)
+}
+
+/** MailboxAccess.Entry — a mailbox of the logged-in user (left menu) */
+export interface MailboxEntry {
+  email: string;
+  displayName: string;
+  kind: 'OWN' | 'MEMBER' | 'ATTACHED';
+  shared: boolean;
+  unread: number;
 }
 
 export interface Attachment {
@@ -53,6 +63,38 @@ export interface Profile {
   usedBytes: number;
   quotaBytes: number;
   createdAt: string;
+  admin?: boolean;        // may manage mailboxes (Settings → Mailboxes)
+}
+
+/** MailboxAdminController.MailboxView */
+export interface Mailbox {
+  id: number;
+  email: string;
+  displayName: string;
+  active: boolean;
+  admin: boolean;
+  trap: boolean;          // what it sends to outside addresses stays in its own INBOX (staging@)
+  shared: boolean;        // shared mailbox: no login of its own, members open it
+  members: string[];      // who may open it
+  usedBytes: number;
+  quotaBytes: number;
+  createdAt: string;
+}
+
+/** MailLists.MailList — mail to the address → a copy to every member, into the folder (null — INBOX) */
+export interface MailList {
+  id: number;
+  address: string;
+  folder: string | null;
+  description: string | null;
+  openToOutside: boolean;
+  members: string[];
+}
+
+/** password — generated by the server, shown once; null when the administrator chose it */
+export interface MailboxCreated {
+  mailbox: Mailbox;
+  password: string | null;
 }
 
 export interface ServerConfig {

frontend/src/app/pages/auth/register.page.ts

@@ -49,13 +49,21 @@ const NAME = /^[a-z0-9]([a-z0-9._-]{0,62}[a-z0-9])?$/;
           </div>
           <div>
             <label class="synth-label" for="password">Password (8+ characters)</label>
-            <input id="password" name="password" type="password" class="synth-input" [ngModel]="password()"
+            <div class="relative"><input id="password" name="password" [type]="show() ? 'text' : 'password'" class="synth-input pr-10" [ngModel]="password()"
                    (ngModelChange)="password.set($event)" required minlength="8" autocomplete="new-password">
+            <button type="button" class="absolute right-2 top-1/2 -translate-y-1/2 text-slate-400 hover:text-cyan-300"
+                    [attr.aria-label]="show() ? 'Hide password' : 'Show password'" (click)="show.set(!show())">
+              <mat-icon>{{ show() ? 'visibility_off' : 'visibility' }}</mat-icon>
+            </button></div>
           </div>
           <div>
             <label class="synth-label" for="password2">Password again</label>
-            <input id="password2" name="password2" type="password" class="synth-input" [ngModel]="password2()"
+            <div class="relative"><input id="password2" name="password2" [type]="show() ? 'text' : 'password'" class="synth-input pr-10" [ngModel]="password2()"
                    (ngModelChange)="password2.set($event)" required autocomplete="new-password">
+            <button type="button" class="absolute right-2 top-1/2 -translate-y-1/2 text-slate-400 hover:text-cyan-300"
+                    [attr.aria-label]="show() ? 'Hide password' : 'Show password'" (click)="show.set(!show())">
+              <mat-icon>{{ show() ? 'visibility_off' : 'visibility' }}</mat-icon>
+            </button></div>
           </div>
           @if (error()) {
             <p class="text-sm text-pink-400 font-rajdhani flex items-center gap-2" role="alert">
@@ -79,6 +87,7 @@ export class RegisterPage {
 
   readonly loaded = signal(false);
   readonly enabled = signal(false);
+  readonly show = signal(false);
   readonly domains = signal<string[]>([]);
   readonly domain = signal('');
   readonly local = signal('');

frontend/src/app/pages/compose/compose.page.ts

@@ -141,6 +141,8 @@ export class ComposePage {
   readonly body = signal('');
   readonly showCc = signal(false);
   readonly draftId = signal<number | null>(null);
+  /** the message being answered: marked answered (and by whom) when this one is sent */
+  private replyToId: number | null = null;
   readonly attachments = signal<Attachment[]>([]);
   readonly dirty = signal(false);
   readonly saving = signal(false);
@@ -207,6 +209,7 @@ export class ComposePage {
   }
 
   private fromReply(m: Message, all: boolean): void {
+    this.replyToId = m.id;
     const me = (this.state.profile()?.email ?? '').toLowerCase();
     this.to.set(m.senderEmail);
     if (all) {
@@ -306,7 +309,7 @@ export class ComposePage {
     const go = () => {
       this.sending.set(true);
       this.error.set('');
-      this.api.send(this.current(), this.draftId()).subscribe({
+      this.api.send(this.current(), this.draftId(), this.replyToId).subscribe({
         next: () => {
           this.done = true;
           this.toasts.ok('Message sent');

frontend/src/app/pages/folder/folder.page.ts

@@ -67,7 +67,7 @@ import { ToastService } from '../../ui/toast.service';
           </div>
         </ng-template>
         <ng-template jtGridCell="subject" let-row>
-          <a [routerLink]="link(row)" class="block max-w-[560px] group">
+          <a [routerLink]="link(row)" class="block max-w-[480px] group">
             <span class="truncate block group-hover:text-cyan-300" [class.font-bold]="!row.read" [class.text-white]="!row.read">
               @if (!row.read) { <span class="inline-block w-2 h-2 rounded-full bg-pink-500 mr-1.5 align-middle shadow-[0_0_8px_#ff007f]" aria-label="Unread"></span> }
               {{ row.subject || '(no subject)' }}

frontend/src/app/pages/message/message.page.ts

@@ -73,6 +73,10 @@ import { ToastService } from '../../ui/toast.service';
             }
             <dt class="text-slate-500 font-mono text-xs pt-0.5">Date</dt>
             <dd class="text-slate-400 font-mono text-xs pt-0.5">{{ m.receivedAt | date: 'EEEE, d MMMM y, HH:mm' }}</dd>
+            @if (m.answeredBy) {
+              <dt class="text-slate-500 font-mono text-xs pt-0.5">Answered</dt>
+              <dd class="text-emerald-300 font-mono text-xs pt-0.5 flex items-center gap-1"><mat-icon class="!text-sm">reply</mat-icon> by {{ m.answeredBy }}</dd>
+            }
           </dl>
         </div>
 

frontend/src/app/pages/settings/lists.section.ts

@@ -0,0 +1,154 @@
+import { ChangeDetectionStrategy, Component, computed, inject, signal } from '@angular/core';
+import { FormsModule } from '@angular/forms';
+import { MatIconModule } from '@angular/material/icon';
+import { ApiService } from '../../core/api.service';
+import { MailList, Mailbox, errorText } from '../../core/models';
+import { ToastService } from '../../ui/toast.service';
+
+/**
+ * Settings → LISTS (administrators): alerts-prod@ → a copy to every member, into the list's folder.
+ * Lists kept by Jambotron are edited here too, but Jambotron puts its own member set back on its next sync.
+ */
+@Component({
+  selector: 'app-lists-section',
+  imports: [FormsModule, MatIconModule],
+  changeDetection: ChangeDetectionStrategy.OnPush,
+  host: { class: 'block xl:col-span-2' },
+  template: `
+    <section class="glass-panel static p-5 md:p-6" aria-labelledby="lists-title">
+      <h2 id="lists-title" class="text-lg font-orbitron font-bold text-cyan-300 flex items-center gap-2 mb-2 border-b border-cyan-500/20 pb-2">
+        <mat-icon class="text-pink-500">forward_to_inbox</mat-icon> LISTS
+      </h2>
+      <p class="text-xs text-slate-400 mb-4">
+        Mail to a list goes to every member — each gets their own copy (own read/unread) in the list's folder.
+        <span class="font-mono">list+tag&#64;</span> puts it into folder «tag» instead. Closed list: only logged-in senders (Kuma, Jambotron).
+      </p>
+
+      <form (ngSubmit)="save()" class="grid grid-cols-1 md:grid-cols-[1fr_1fr_1fr] gap-3 mb-3">
+        <div><label class="synth-label" for="ls-address">Address</label>
+          <div class="flex items-stretch gap-2">
+            <input id="ls-address" name="address" class="synth-input" [ngModel]="local()" (ngModelChange)="local.set($event.toLowerCase().trim())"
+                   placeholder="alerts-prod" autocomplete="off" required [readonly]="editing()">
+            <span class="flex items-center text-cyan-300 font-mono">&#64;</span>
+            <span class="flex items-center px-3 rounded-[10px] bg-slate-900/70 border border-cyan-500/30 font-mono text-sm text-slate-200 whitespace-nowrap">{{ domain() }}</span>
+          </div></div>
+        <div><label class="synth-label" for="ls-folder">Folder (empty — INBOX)</label>
+          <input id="ls-folder" name="folder" class="synth-input" [(ngModel)]="folder" maxlength="50" placeholder="prod" autocomplete="off"></div>
+        <div><label class="synth-label" for="ls-about">Description</label>
+          <input id="ls-about" name="about" class="synth-input" [(ngModel)]="description" maxlength="255" autocomplete="off"></div>
+        <fieldset class="md:col-span-3">
+          <legend class="synth-label">Members</legend>
+          <div class="flex flex-wrap gap-x-4 gap-y-1">
+            @for (m of mailboxes(); track m.id) {
+              <label class="flex items-center gap-1.5 text-sm font-mono" [class.text-slate-500]="!m.active">
+                <input type="checkbox" [checked]="members().has(m.email)" (change)="flip(m.email)"> {{ m.email }}
+              </label>
+            }
+          </div>
+        </fieldset>
+        <div class="md:col-span-3 flex flex-wrap items-center gap-3">
+          <label class="flex items-center gap-1.5 text-sm"><input type="checkbox" name="open" [(ngModel)]="openToOutside"> open to anyone (not only logged-in senders)</label>
+          <span class="ml-auto"></span>
+          @if (editing()) { <button type="button" class="ghost-btn !py-1" (click)="reset()"><mat-icon>close</mat-icon> CANCEL</button> }
+          <button type="submit" class="cyber-btn px-4 py-2 rounded-lg text-xs font-bold" [disabled]="busy()">
+            <mat-icon>{{ editing() ? 'save' : 'add' }}</mat-icon> {{ editing() ? 'SAVE' : 'CREATE' }}</button>
+        </div>
+      </form>
+      @if (error()) { <p class="text-sm text-pink-400 mb-3" role="alert">{{ error() }}</p> }
+
+      <ul class="divide-y divide-cyan-500/10">
+        @for (l of lists(); track l.id) {
+          <li class="py-2">
+            <div class="flex flex-wrap items-center gap-x-4 gap-y-1">
+              <span class="font-mono text-sm text-cyan-300">{{ l.address }}</span>
+              <span class="text-xs font-mono text-slate-400">→ {{ l.folder || 'INBOX' }}</span>
+              @if (l.openToOutside) { <span class="text-[10px] font-mono px-1.5 rounded border border-amber-400/50 text-amber-300">OPEN</span> }
+              <span class="text-sm text-slate-400">{{ l.description }}</span>
+              <span class="ml-auto"></span>
+              <button type="button" class="ghost-btn !py-1" (click)="edit(l)" [attr.aria-label]="'Edit ' + l.address"><mat-icon>edit</mat-icon></button>
+              <button type="button" class="ghost-btn !py-1" (click)="remove(l)" [attr.aria-label]="'Delete ' + l.address"><mat-icon>delete</mat-icon></button>
+            </div>
+            <div class="text-xs font-mono text-slate-500 mt-0.5">{{ l.members.length ? l.members.join(', ') : 'no members — mail to it is dropped' }}</div>
+          </li>
+        } @empty {
+          <li class="py-2 text-sm text-slate-500">No lists yet.</li>
+        }
+      </ul>
+    </section>
+  `
+})
+export class ListsSection {
+  private api = inject(ApiService);
+  private toasts = inject(ToastService);
+
+  readonly lists = signal<MailList[]>([]);
+  readonly mailboxes = signal<Mailbox[]>([]);
+  readonly members = signal<Set<string>>(new Set());
+  readonly local = signal('');
+  readonly domains = signal<string[]>([]);
+  readonly domain = computed(() => this.domains()[0] ?? '');
+  readonly editing = signal(false);
+  readonly error = signal('');
+  readonly busy = signal(false);
+  folder = '';
+  description = '';
+  openToOutside = false;
+
+  constructor() {
+    this.api.config().subscribe({ next: c => this.domains.set(c.domains), error: () => {} });
+    this.api.mailboxes().subscribe({ next: list => this.mailboxes.set(list), error: () => {} });
+    this.load();
+  }
+
+  load(): void {
+    this.api.mailLists().subscribe({ next: list => this.lists.set(list), error: e => this.error.set(errorText(e)) });
+  }
+
+  flip(email: string): void {
+    const next = new Set(this.members());
+    if (next.has(email)) { next.delete(email); } else { next.add(email); }
+    this.members.set(next);
+  }
+
+  edit(l: MailList): void {
+    this.local.set(l.address.split('@')[0]);
+    this.domains.set([l.address.split('@')[1], ...this.domains().filter(d => d !== l.address.split('@')[1])]);
+    this.folder = l.folder ?? '';
+    this.description = l.description ?? '';
+    this.openToOutside = l.openToOutside;
+    this.members.set(new Set(l.members));
+    this.editing.set(true);
+    this.error.set('');
+  }
+
+  reset(): void {
+    this.local.set('');
+    this.folder = this.description = '';
+    this.openToOutside = false;
+    this.members.set(new Set());
+    this.editing.set(false);
+  }
+
+  save(): void {
+    const local = this.local().replace(/@.*$/, '');
+    if (!local) { this.error.set('Enter an address'); return; }
+    const address = local + '@' + this.domain();
+    this.error.set('');
+    this.busy.set(true);
+    this.api.saveMailList(address, {
+      folder: this.folder.trim(), description: this.description.trim(), openToOutside: this.openToOutside,
+      members: [...this.members()]
+    }).subscribe({
+      next: saved => { this.busy.set(false); this.toasts.ok('List ' + saved.address + ' saved'); this.reset(); this.load(); },
+      error: e => { this.busy.set(false); this.error.set(errorText(e)); }
+    });
+  }
+
+  remove(l: MailList): void {
+    if (!confirm('Delete list ' + l.address + '? Mail to it will be refused.')) return;
+    this.api.deleteMailList(l.address).subscribe({
+      next: () => { this.toasts.ok('List ' + l.address + ' deleted'); this.load(); },
+      error: e => this.toasts.error(errorText(e))
+    });
+  }
+}

frontend/src/app/pages/settings/mailboxes.section.ts

@@ -0,0 +1,233 @@
+import { ChangeDetectionStrategy, Component, computed, inject, signal } from '@angular/core';
+import { FormsModule } from '@angular/forms';
+import { MatIconModule } from '@angular/material/icon';
+import { ApiService } from '../../core/api.service';
+import { MailStateService } from '../../core/mail-state.service';
+import { Mailbox, errorText, formatBytes } from '../../core/models';
+import { ToastService } from '../../ui/toast.service';
+import { AuthService } from '../../core/auth.service';
+
+/** Settings → Mailboxes (administrators): create no-reply@, monitor@, support@ …, new password, switch off. */
+@Component({
+  selector: 'app-mailboxes-section',
+  imports: [FormsModule, MatIconModule],
+  changeDetection: ChangeDetectionStrategy.OnPush,
+  // ячейка сетки настроек — сам элемент компонента: на две колонки
+  host: { class: 'block xl:col-span-2' },
+  template: `
+    <section class="glass-panel static p-5 md:p-6" aria-labelledby="mailboxes-title">
+      <h2 id="mailboxes-title" class="text-lg font-orbitron font-bold text-cyan-300 flex items-center gap-2 mb-4 border-b border-cyan-500/20 pb-2">
+        <mat-icon class="text-pink-500">group</mat-icon> MAILBOXES
+      </h2>
+
+      <form (ngSubmit)="create()" class="grid grid-cols-1 md:grid-cols-[1fr_1fr_1fr_auto] gap-3 items-end mb-4">
+        <div><label class="synth-label" for="mb-email">Address</label>
+          <div class="flex items-stretch gap-2">
+            <input id="mb-email" name="email" class="synth-input" [ngModel]="local()" (ngModelChange)="local.set($event.toLowerCase().trim())"
+                   placeholder="no-reply" autocomplete="off" required>
+            <span class="flex items-center text-cyan-300 font-mono">&#64;</span>
+            @if (domains().length > 1) {
+              <select name="domain" class="synth-input !w-auto" [ngModel]="domain()" (ngModelChange)="domain.set($event)" aria-label="Domain">
+                @for (d of domains(); track d) { <option [value]="d">{{ d }}</option> }
+              </select>
+            } @else {
+              <span class="flex items-center px-3 rounded-[10px] bg-slate-900/70 border border-cyan-500/30 font-mono text-sm text-slate-200 whitespace-nowrap">{{ domain() }}</span>
+            }
+          </div></div>
+        <div><label class="synth-label" for="mb-name">Name</label>
+          <input id="mb-name" name="name" class="synth-input" [(ngModel)]="name" maxlength="100" autocomplete="off"></div>
+        <div><label class="synth-label" for="mb-password">Password (empty — generate)</label>
+          <div class="relative"><input id="mb-password" name="password" [type]="showPw() ? 'text' : 'password'" class="synth-input pr-10" [(ngModel)]="password" autocomplete="new-password">
+            <button type="button" class="absolute right-2 top-1/2 -translate-y-1/2 text-slate-400 hover:text-cyan-300"
+                    [attr.aria-label]="showPw() ? 'Hide password' : 'Show password'" (click)="showPw.set(!showPw())">
+              <mat-icon>{{ showPw() ? 'visibility_off' : 'visibility' }}</mat-icon>
+            </button></div></div>
+        <button type="submit" class="cyber-btn px-4 py-2 rounded-lg text-xs font-bold" [disabled]="busy()"><mat-icon>add</mat-icon> CREATE</button>
+        <label class="md:col-span-4 flex items-center gap-1.5 text-sm text-slate-300">
+          <input type="checkbox" name="shared" [(ngModel)]="shared">
+          shared mailbox (support&#64;, billing&#64;): no password of its own — members open it from their mailbox, read/unread is common
+        </label>
+      </form>
+      @if (error()) { <p class="text-sm text-pink-400 mb-3" role="alert">{{ error() }}</p> }
+
+      @if (secret(); as s) {
+        <div class="p-3 mb-4 rounded-lg border border-pink-500/40 bg-slate-900/60" role="status">
+          <div class="text-xs text-slate-400 mb-1">Password of <span class="font-mono text-cyan-300">{{ s.email }}</span> — shown once, copy it now</div>
+          <div class="flex items-center gap-2">
+            <code class="font-mono text-pink-300 break-all select-all">{{ s.password }}</code>
+            <button type="button" class="ghost-btn !py-1" (click)="copy(s.password)" aria-label="Copy password"><mat-icon>content_copy</mat-icon></button>
+            <button type="button" class="ghost-btn !py-1" (click)="secret.set(null)" aria-label="Hide password"><mat-icon>close</mat-icon></button>
+          </div>
+        </div>
+      }
+
+      <ul class="divide-y divide-cyan-500/10">
+        @for (m of mailboxes(); track m.id) {
+          <li class="flex flex-wrap items-center gap-x-4 gap-y-1 py-2">
+            <span class="font-mono text-sm" [class.text-cyan-300]="m.active" [class.text-slate-500]="!m.active" [class.line-through]="!m.active">{{ m.email }}</span>
+            <span class="text-sm text-slate-400">{{ m.displayName }}</span>
+            @if (m.admin) { <span class="text-[10px] font-mono px-1.5 rounded border border-pink-500/40 text-pink-300">ADMIN</span> }
+            @if (m.shared) { <span class="text-[10px] font-mono px-1.5 rounded border border-cyan-400/50 text-cyan-300"
+                                   [title]="'Members: ' + (m.members.join(', ') || 'none')">SHARED · {{ m.members.length }}</span> }
+            @if (!m.shared && m.members.length) { <span class="text-[10px] font-mono px-1.5 rounded border border-cyan-400/30 text-cyan-300/80"
+                                   [title]="'Also opened by: ' + m.members.join(', ')">+{{ m.members.length }}</span> }
+            @if (m.trap) { <span class="text-[10px] font-mono px-1.5 rounded border border-amber-400/50 text-amber-300"
+                                 title="What it sends is kept in its own INBOX — nothing leaves the server">TRAP</span> }
+            <span class="text-xs font-mono text-slate-500 ml-auto">{{ size(m.usedBytes) }}</span>
+            @if (m.email !== me()) {
+              <button type="button" class="ghost-btn !py-1" (click)="open(m)" [attr.aria-label]="'Open ' + m.email" title="Open mailbox">
+                <mat-icon>mark_email_read</mat-icon> OPEN</button>
+            }
+            <button type="button" class="ghost-btn !py-1" (click)="editMembers(m)" [attr.aria-expanded]="membersOf() === m.id"
+                    [attr.aria-label]="'Who may open ' + m.email" title="Who may open this mailbox"><mat-icon>group</mat-icon></button>
+            <button type="button" class="ghost-btn !py-1" (click)="trap(m)" [class.text-amber-300]="m.trap"
+                    [attr.aria-label]="(m.trap ? 'Trap off for ' : 'Trap on for ') + m.email"
+                    [title]="m.trap ? 'Trap ON: sent mail stays in its INBOX. Click to send for real' : 'Trap: keep what it sends in its own INBOX'">
+              <mat-icon>{{ m.trap ? 'move_to_inbox' : 'outbox' }}</mat-icon></button>
+            @if (!m.shared) {
+              <button type="button" class="ghost-btn !py-1" (click)="newPassword(m)" [attr.aria-label]="'New password for ' + m.email"><mat-icon>key</mat-icon></button>
+            }
+            @if (m.email !== me()) {
+              <button type="button" class="ghost-btn !py-1" (click)="toggle(m)"
+                      [attr.aria-label]="(m.active ? 'Switch off ' : 'Switch on ') + m.email">
+                <mat-icon>{{ m.active ? 'toggle_on' : 'toggle_off' }}</mat-icon></button>
+            }
+            @if (membersOf() === m.id) {
+              <div class="basis-full mt-1 p-2 rounded-lg border border-cyan-500/20">
+                <div class="text-xs text-slate-400 mb-1">Who may open <span class="font-mono text-cyan-300">{{ m.email }}</span> from their own mailbox:</div>
+                <div class="flex flex-wrap gap-x-4 gap-y-1">
+                  @for (o of mailboxes(); track o.id) {
+                    @if (o.id !== m.id && !o.shared) {
+                      <label class="flex items-center gap-1.5 text-sm font-mono">
+                        <input type="checkbox" [checked]="picked().has(o.email)" (change)="pick(o.email)"> {{ o.email }}
+                      </label>
+                    }
+                  }
+                </div>
+                <div class="flex gap-2 mt-2">
+                  <button type="button" class="cyber-btn px-3 py-1 rounded-lg text-xs font-bold" (click)="saveMembers(m)"><mat-icon>save</mat-icon> SAVE</button>
+                  <button type="button" class="ghost-btn !py-1" (click)="membersOf.set(null)">CANCEL</button>
+                </div>
+              </div>
+            }
+          </li>
+        }
+      </ul>
+    </section>
+  `
+})
+export class MailboxesSection {
+  private api = inject(ApiService);
+  private state = inject(MailStateService);
+  private toasts = inject(ToastService);
+  private auth = inject(AuthService);
+
+  readonly mailboxes = signal<Mailbox[]>([]);
+  readonly secret = signal<{ email: string; password: string } | null>(null);
+  readonly error = signal('');
+  readonly busy = signal(false);
+  readonly me = computed(() => this.state.profile()?.email ?? '');
+  readonly showPw = signal(false);
+  readonly local = signal('');
+  // Домены сервера (/api/config); пока не пришли — домен своего ящика
+  readonly domains = signal<string[]>([]);
+  readonly domain = signal('');
+  name = '';
+  password = '';
+  shared = false;
+  /** mailbox whose members are being edited */
+  readonly membersOf = signal<number | null>(null);
+  readonly picked = signal<Set<string>>(new Set());
+
+  constructor() {
+    this.domain.set(this.me().split('@')[1] ?? '');
+    this.api.config().subscribe({
+      next: c => { this.domains.set(c.domains); if (!c.domains.includes(this.domain())) { this.domain.set(c.domains[0] ?? ''); } },
+      error: () => {}
+    });
+    this.load();
+  }
+
+  size(bytes: number): string {
+    return formatBytes(bytes);
+  }
+
+  load(): void {
+    this.api.mailboxes().subscribe({ next: list => this.mailboxes.set(list), error: e => this.error.set(errorText(e)) });
+  }
+
+  create(): void {
+    const local = this.local().replace(/@.*$/, '');
+    if (!local) { this.error.set('Enter an address'); return; }
+    const email = local + '@' + this.domain();
+    this.error.set('');
+    this.busy.set(true);
+    this.api.createMailbox(email, this.name.trim(), this.password, this.shared).subscribe({
+      next: created => {
+        this.busy.set(false);
+        this.local.set('');
+        this.name = this.password = '';
+        this.shared = false;
+        if (created.password) { this.secret.set({ email: created.mailbox.email, password: created.password }); }
+        this.toasts.ok('Mailbox ' + created.mailbox.email + ' created');
+        this.load();
+      },
+      error: e => { this.busy.set(false); this.error.set(errorText(e)); }
+    });
+  }
+
+  newPassword(m: Mailbox): void {
+    if (!confirm('New password for ' + m.email + '? The old one stops working at once.')) return;
+    this.api.newMailboxPassword(m.id).subscribe({
+      next: created => created.password && this.secret.set({ email: m.email, password: created.password }),
+      error: e => this.toasts.error(errorText(e))
+    });
+  }
+
+  /** Administrator reads this mailbox: its session; the banner on top leads back. Full reload — fresh folders. */
+  open(m: Mailbox): void {
+    this.api.openMailbox(m.id).subscribe({
+      next: session => { this.auth.openAs(session); location.assign('/'); },
+      error: e => this.toasts.error(errorText(e))
+    });
+  }
+
+  /** Trap on: what the mailbox sends is kept in its own INBOX (staging@). Off: it sends for real again. */
+  trap(m: Mailbox): void {
+    if (m.trap && !confirm('Switch the trap off? ' + m.email + ' will send mail to real people again.')) return;
+    this.api.setMailboxTrap(m.id, !m.trap).subscribe({
+      next: () => { this.toasts.ok('Trap ' + (m.trap ? 'off' : 'on') + ' for ' + m.email); this.load(); },
+      error: e => this.toasts.error(errorText(e))
+    });
+  }
+
+  editMembers(m: Mailbox): void {
+    if (this.membersOf() === m.id) { this.membersOf.set(null); return; }
+    this.picked.set(new Set(m.members));
+    this.membersOf.set(m.id);
+  }
+
+  pick(email: string): void {
+    const next = new Set(this.picked());
+    if (next.has(email)) { next.delete(email); } else { next.add(email); }
+    this.picked.set(next);
+  }
+
+  saveMembers(m: Mailbox): void {
+    this.api.setMailboxMembers(m.id, [...this.picked()]).subscribe({
+      next: () => { this.toasts.ok('Members of ' + m.email + ' saved'); this.membersOf.set(null); this.load(); },
+      error: e => this.toasts.error(errorText(e))
+    });
+  }
+
+  toggle(m: Mailbox): void {
+    this.api.setMailboxActive(m.id, !m.active).subscribe({
+      next: () => this.load(),
+      error: e => this.toasts.error(errorText(e))
+    });
+  }
+
+  copy(text: string): void {
+    navigator.clipboard?.writeText(text).then(() => this.toasts.ok('Copied'), () => this.toasts.error('Copy it by hand'));
+  }
+}

frontend/src/app/pages/settings/settings.page.ts

@@ -7,11 +7,13 @@ import { MailStateService } from '../../core/mail-state.service';
 import { errorText, formatBytes } from '../../core/models';
 import { THEMES, ThemeService } from '../../ui/theme.service';
 import { ToastService } from '../../ui/toast.service';
+import { MailboxesSection } from './mailboxes.section';
+import { ListsSection } from './lists.section';
 
 /** Profile name, password, storage, look. */
 @Component({
   selector: 'app-settings',
-  imports: [DatePipe, FormsModule, MatIconModule],
+  imports: [DatePipe, FormsModule, MatIconModule, MailboxesSection, ListsSection],
   changeDetection: ChangeDetectionStrategy.OnPush,
   template: `
     <div class="grid grid-cols-1 xl:grid-cols-2 gap-5">
@@ -41,11 +43,23 @@ import { ToastService } from '../../ui/toast.service';
         <form (ngSubmit)="changePassword()" class="space-y-3">
           <input type="email" name="username" class="sr-only" [value]="state.profile()?.email ?? ''" autocomplete="username" tabindex="-1" aria-hidden="true">
           <div><label class="synth-label" for="pw-current">Current password</label>
-            <input id="pw-current" name="current" type="password" class="synth-input" [(ngModel)]="current" autocomplete="current-password"></div>
+            <div class="relative"><input id="pw-current" name="current" [type]="showPw() ? 'text' : 'password'" class="synth-input pr-10" [(ngModel)]="current" autocomplete="current-password">
+            <button type="button" class="absolute right-2 top-1/2 -translate-y-1/2 text-slate-400 hover:text-cyan-300"
+                    [attr.aria-label]="showPw() ? 'Hide password' : 'Show password'" (click)="showPw.set(!showPw())">
+              <mat-icon>{{ showPw() ? 'visibility_off' : 'visibility' }}</mat-icon>
+            </button></div></div>
           <div><label class="synth-label" for="pw-new">New password (8+ characters)</label>
-            <input id="pw-new" name="next" type="password" class="synth-input" [(ngModel)]="next" autocomplete="new-password"></div>
+            <div class="relative"><input id="pw-new" name="next" [type]="showPw() ? 'text' : 'password'" class="synth-input pr-10" [(ngModel)]="next" autocomplete="new-password">
+            <button type="button" class="absolute right-2 top-1/2 -translate-y-1/2 text-slate-400 hover:text-cyan-300"
+                    [attr.aria-label]="showPw() ? 'Hide password' : 'Show password'" (click)="showPw.set(!showPw())">
+              <mat-icon>{{ showPw() ? 'visibility_off' : 'visibility' }}</mat-icon>
+            </button></div></div>
           <div><label class="synth-label" for="pw-again">New password again</label>
-            <input id="pw-again" name="again" type="password" class="synth-input" [(ngModel)]="again" autocomplete="new-password"></div>
+            <div class="relative"><input id="pw-again" name="again" [type]="showPw() ? 'text' : 'password'" class="synth-input pr-10" [(ngModel)]="again" autocomplete="new-password">
+            <button type="button" class="absolute right-2 top-1/2 -translate-y-1/2 text-slate-400 hover:text-cyan-300"
+                    [attr.aria-label]="showPw() ? 'Hide password' : 'Show password'" (click)="showPw.set(!showPw())">
+              <mat-icon>{{ showPw() ? 'visibility_off' : 'visibility' }}</mat-icon>
+            </button></div></div>
           @if (passwordError()) { <p class="text-sm text-pink-400" role="alert">{{ passwordError() }}</p> }
           <button type="submit" class="cyber-btn px-4 py-2 rounded-lg text-xs font-bold"><mat-icon>lock_reset</mat-icon> CHANGE PASSWORD</button>
         </form>
@@ -97,6 +111,11 @@ import { ToastService } from '../../ui/toast.service';
           </div>
         </div>
       </section>
+
+      @if (state.profile()?.admin) {
+        <app-mailboxes-section />
+        <app-lists-section />
+      }
     </div>
   `
 })
@@ -112,6 +131,7 @@ export class SettingsPage {
   next = '';
   again = '';
   readonly passwordError = signal('');
+  readonly showPw = signal(false);
 
   readonly used = computed(() => formatBytes(this.state.profile()?.usedBytes));
   readonly quota = computed(() => formatBytes(this.state.profile()?.quotaBytes));

frontend/src/app/pages/shell/shell.component.ts

@@ -8,7 +8,7 @@ import { filter } from 'rxjs';
 import { ApiService } from '../../core/api.service';
 import { AuthService } from '../../core/auth.service';
 import { MailStateService } from '../../core/mail-state.service';
-import { Folder, errorText, folderIcon, folderLabel, formatBytes } from '../../core/models';
+import { Folder, MailboxEntry, errorText, folderIcon, folderLabel, formatBytes } from '../../core/models';
 import { BackgroundComponent } from '../../ui/background.component';
 import { DialogService } from '../../ui/dialog.service';
 import { THEMES, ThemeService } from '../../ui/theme.service';
@@ -69,9 +69,56 @@ import { ToastService } from '../../ui/toast.service';
         </div>
       </header>
 
+      @if (auth.openedBy(); as admin) {
+        <div class="bg-pink-600/90 text-white text-sm font-rajdhani px-4 py-2 flex flex-wrap items-center justify-center gap-3" role="status">
+          <mat-icon class="!text-base">visibility</mat-icon>
+          <span>You are in mailbox <b class="font-mono">{{ auth.email() }}</b> as administrator</span>
+          <button type="button" class="ghost-btn !py-1 !border-white !text-white" (click)="backToAdmin()">
+            <mat-icon>arrow_back</mat-icon> Back to {{ admin }}</button>
+        </div>
+      }
+
       <div class="flex-grow max-w-[1500px] w-full mx-auto p-3 md:p-5 grid grid-cols-1 lg:grid-cols-[260px_1fr] gap-5">
-        <nav class="glass-panel static p-4 h-fit lg:sticky lg:top-24 lg:block" [class.hidden]="!menuOpen()"
+        <nav class="glass-panel static p-4 md:pt-6 h-fit lg:sticky lg:top-20 lg:block" [class.hidden]="!menuOpen()"
              aria-label="Mail folders">
+          <div class="flex items-center justify-between mb-2 px-1">
+            <h2 class="text-[11px] font-orbitron font-bold text-cyan-300 tracking-widest">MAILBOXES</h2>
+            <button type="button" class="text-slate-400 hover:text-cyan-300" matTooltip="Add a mailbox you have the password of"
+                    aria-label="Add mailbox" [attr.aria-expanded]="attachOpen()" (click)="attachOpen.set(!attachOpen())">
+              <mat-icon class="!text-xl">add_circle_outline</mat-icon></button>
+          </div>
+          <ul class="space-y-1 mb-3" aria-label="Your mailboxes">
+            @for (b of boxes(); track b.email) {
+              <li class="flex items-center gap-1">
+                <button type="button" (click)="switchTo(b)" [attr.aria-current]="b.email === auth.email() ? 'true' : null"
+                        class="flex-grow flex items-center gap-2 px-3 py-1.5 rounded-lg border text-left font-rajdhani font-semibold min-w-0"
+                        [class.border-pink-500/40]="b.email === auth.email()" [class.bg-pink-500/15]="b.email === auth.email()"
+                        [class.text-pink-200]="b.email === auth.email()" [class.border-transparent]="b.email !== auth.email()"
+                        [class.text-slate-300]="b.email !== auth.email()"
+                        [matTooltip]="b.email + (b.shared ? ' — shared' : b.kind === 'ATTACHED' ? ' — attached' : '')">
+                  <mat-icon class="!text-lg shrink-0">{{ b.shared ? 'groups' : b.kind === 'OWN' ? 'person' : 'link' }}</mat-icon>
+                  <span class="flex-grow truncate text-sm">{{ b.email }}</span>
+                  @if (b.unread) {
+                    <span class="text-[11px] font-mono px-2 rounded-full bg-pink-500/25 text-pink-300" [attr.aria-label]="b.unread + ' unread'">{{ b.unread }}</span>
+                  }
+                </button>
+                @if (b.kind !== 'OWN') {
+                  <button type="button" class="text-slate-500 hover:text-pink-400" [attr.aria-label]="'Remove ' + b.email + ' from my mailboxes'"
+                          matTooltip="Remove from my mailboxes" (click)="leave(b)"><mat-icon class="!text-base">close</mat-icon></button>
+                }
+              </li>
+            }
+          </ul>
+          @if (attachOpen()) {
+            <form class="space-y-2 mb-4 p-2 rounded-lg border border-cyan-500/20" (ngSubmit)="attach()" aria-label="Add a mailbox">
+              <label class="synth-label" for="att-email">Mailbox</label>
+              <input id="att-email" name="attEmail" class="synth-input !py-1.5" [(ngModel)]="attachEmail" autocomplete="off" placeholder="name&#64;domain">
+              <label class="synth-label" for="att-pw">Its password</label>
+              <input id="att-pw" name="attPw" type="password" class="synth-input !py-1.5" [(ngModel)]="attachPassword" autocomplete="off">
+              <button type="submit" class="cyber-btn w-full py-1.5 rounded-lg text-xs font-bold"><mat-icon>link</mat-icon> ADD</button>
+            </form>
+          }
+
           <a routerLink="/compose" class="cyber-btn w-full py-2.5 rounded-xl font-bold text-xs mb-4" (click)="menuOpen.set(false)">
             <mat-icon>edit</mat-icon> COMPOSE
           </a>
@@ -156,6 +203,11 @@ export class ShellComponent {
 
   readonly themes = THEMES;
   readonly menuOpen = signal(false);
+  /** own, shared and attached mailboxes of the login (shown when there is more than the own one, or to add one) */
+  readonly boxes = signal<MailboxEntry[]>([]);
+  readonly attachOpen = signal(false);
+  attachEmail = '';
+  attachPassword = '';
   query = '';
 
   readonly links = [
@@ -186,7 +238,8 @@ export class ShellComponent {
   constructor() {
     this.state.refreshFolders();
     this.state.refreshProfile();
-    const timer = setInterval(() => this.state.refreshFolders(), 30000);
+    this.loadBoxes();
+    const timer = setInterval(() => { this.state.refreshFolders(); this.loadBoxes(); }, 30000);
     inject(DestroyRef).onDestroy(() => clearInterval(timer));
     this.router.events.pipe(filter(e => e instanceof NavigationEnd)).subscribe(() => {
       const q = this.router.parseUrl(this.router.url).queryParams['q'];
@@ -247,6 +300,57 @@ export class ShellComponent {
     }
   }
 
+  loadBoxes(): void {
+    this.api.myMailboxes().subscribe({ next: list => this.boxes.set(list), error: () => {} });
+  }
+
+  /** Another mailbox of this login: its session, full reload — fresh folders and profile. */
+  switchTo(b: MailboxEntry): void {
+    if (b.email === this.auth.email()) { this.router.navigate(['/']); return; }
+    this.api.mailboxSession(b.email).subscribe({
+      next: session => { this.state.reset(); this.auth.switchTo(session); location.assign('/'); },
+      error: e => this.toasts.error(errorText(e))
+    });
+  }
+
+  attach(): void {
+    const email = this.attachEmail.trim().toLowerCase();
+    if (!email || !this.attachPassword) { this.toasts.error('Mailbox and its password'); return; }
+    this.api.attachMailbox(email, this.attachPassword).subscribe({
+      next: b => {
+        this.attachEmail = this.attachPassword = '';
+        this.attachOpen.set(false);
+        this.toasts.ok(b.email + ' added to your mailboxes');
+        this.loadBoxes();
+      },
+      error: e => this.toasts.error(errorText(e))
+    });
+  }
+
+  leave(b: MailboxEntry): void {
+    this.dialogs.confirm(`Remove ${b.email}?`, b.shared
+      ? 'It disappears from your menu. An administrator can give it back.'
+      : 'It disappears from your menu. Add it again with its password.', 'Remove', true).subscribe(ok => {
+      if (ok === null) return;
+      this.api.leaveMailbox(b.email).subscribe({
+        next: () => {
+          this.toasts.ok(b.email + ' removed');
+          if (b.email === this.auth.email()) {
+            const own = this.boxes().find(x => x.kind === 'OWN');
+            if (own) { this.switchTo(own); return; }
+          }
+          this.loadBoxes();
+        },
+        error: e => this.toasts.error(errorText(e))
+      });
+    });
+  }
+
+  backToAdmin(): void {
+    this.auth.backToAdmin();
+    location.assign('/settings');
+  }
+
   logout(): void {
     this.state.reset();
     this.auth.logout();