Администраторы почты из Jambotron: каждый ADMIN управляет ящиками

users.is_admin (V8) — ставит только служебное API (PUT /api/service/accounts
с "admin"), ящик сам себя администратором не сделает. MailAdmins: список из
конфигурации + выданные Jambotron (загружаются при старте, меняются сразу).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

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

@@ -10,13 +10,15 @@ 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.
+ * mailbox — {@code mailserver.admin.email}, or admin@<first domain>; plus mailboxes Jambotron marks as admin
+ * through the service API ({@code users.is_admin}, V8 — every Jambotron ADMIN). A mailbox can not make itself an
+ * administrator: only the configuration or the service token.
  */
 @Component
 public class MailAdmins {
 
     private final Set<String> admins;
+    private final Set<String> granted = java.util.concurrent.ConcurrentHashMap.newKeySet();
 
     public MailAdmins(@Value("${mailserver.admins:}") String admins,
                       @Value("${mailserver.admin.email:}") String firstMailbox,
@@ -31,6 +33,20 @@ public class MailAdmins {
     }
 
     public boolean isAdmin(String email) {
-        return email != null && admins.contains(email.toLowerCase(Locale.ROOT));
+        if (email == null) {
+            return false;
+        }
+        String key = email.toLowerCase(Locale.ROOT);
+        return admins.contains(key) || granted.contains(key);
+    }
+
+    /** Given / taken by Jambotron (users.is_admin) — loaded at start and kept here on every change. */
+    public void grant(String email, boolean admin) {
+        String key = email.toLowerCase(Locale.ROOT);
+        if (admin) {
+            granted.add(key);
+        } else {
+            granted.remove(key);
+        }
     }
 }

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

@@ -0,0 +1,32 @@
+package com.mailserver.config;
+
+import com.mailserver.repository.UserRepository;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.boot.context.event.ApplicationReadyEvent;
+import org.springframework.context.event.EventListener;
+import org.springframework.stereotype.Component;
+
+/** At start: mailboxes Jambotron made administrators (users.is_admin) → {@link MailAdmins}. */
+@Component
+public class MailAdminsLoader {
+
+    private static final Logger log = LoggerFactory.getLogger(MailAdminsLoader.class);
+
+    private final UserRepository users;
+    private final MailAdmins admins;
+
+    public MailAdminsLoader(UserRepository users, MailAdmins admins) {
+        this.users = users;
+        this.admins = admins;
+    }
+
+    @EventListener(ApplicationReadyEvent.class)
+    public void load() {
+        users.findAll().filter(user -> user.isAdmin())
+                .doOnNext(user -> admins.grant(user.getEmail(), true))
+                .count()
+                .subscribe(n -> log.info("Mail administrators from Jambotron: {}", n),
+                        e -> log.error("Mail administrators from Jambotron not loaded: {}", e.getMessage()));
+    }
+}