Feature: recipient autocomplete from Sent, with on-demand server search

Compose recipient fields only suggested existing contacts and directory
users, so people you had emailed before but never saved as a contact
never came up. This adds an Outlook-Web-style suggestion flow.

On startup the Sent folder is read once (metadata only) to build a cache
of addresses you have written to; those are merged into the autocomplete
after contacts and directory principals, deduped, contacts winning.

When the recipient is not in the cache, the dropdown offers a "search the
server" row that queries the Sent folder on demand. That lookup fetches
only the to/cc fields (no subject, body or attachments) and returns the
matching addresses, deduped.

New strings are added to all 20 locales.

app/(main)/[locale]/page.tsx

@@ -121,7 +121,7 @@ export default function Home() {
   useIdentitySync();
   const trustedSendersAddressBook = useSettingsStore((state) => state.trustedSendersAddressBook);
   const sendDelaySeconds = useSettingsStore((state) => state.sendDelaySeconds);
-  const { loadTrustedSendersBook, trustedSendersLoaded } = useContactStore();
+  const { loadTrustedSendersBook, trustedSendersLoaded, loadRecentRecipients } = useContactStore();
 
   const promptForRescheduleDelayedUntil = useCallback((): string | null => {
     const value = window.prompt(t('email_viewer.reschedule_prompt'));
@@ -342,6 +342,15 @@ export default function Home() {
     refreshCurrentMailbox,
   } = useEmailStore();
 
+  // Load recent recipients (from the Sent folder) for compose autocomplete.
+  // Runs once when the Sent mailbox is known; the store guards against reloads.
+  useEffect(() => {
+    const sent = mailboxes.find((m) => m.role === 'sent');
+    if (client && sent) {
+      loadRecentRecipients(client, sent.originalId || sent.id);
+    }
+  }, [client, mailboxes, loadRecentRecipients]);
+
   // Pro shell: populate per-account mailbox cache so the sidebar can render
   // every connected account Thunderbird-style.
   useProMultiAccountMailboxes();

components/email/email-composer.tsx

@@ -5,7 +5,7 @@ import { useFocusTrap } from "@/hooks/use-focus-trap";
 import { useTranslations } from "next-intl";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
-import { X, Paperclip, Send, Save, Check, Loader2, AlertCircle, FileText, BookmarkPlus, CalendarClock, ChevronDown, MailCheck } from "lucide-react";
+import { X, Paperclip, Send, Save, Check, Loader2, AlertCircle, FileText, BookmarkPlus, CalendarClock, ChevronDown, MailCheck, Search } from "lucide-react";
 import { cn, formatFileSize, formatDateTime, generateUUID } from "@/lib/utils";
 import { debug } from "@/lib/debug";
 import { toast } from "@/stores/toast-store";
@@ -820,6 +820,10 @@ export function EmailComposer({
       ? `<div>${getPlainTextSignature(signatureIdentity).replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;').replace(/\n/g, '<br>')}</div>`
       : '';
   const getAutocomplete = useContactStore((s) => s.getAutocomplete);
+  const searchRecipients = useContactStore((s) => s.searchRecipients);
+  // Whether a Sent mailbox is known so the on-demand server search is worth
+  // offering (falls back to hiding the "search the server" row otherwise).
+  const canSearchServer = useContactStore((s) => s.sentMailboxId != null);
   const addToTrustedSendersBook = useContactStore((s) => s.addToTrustedSendersBook);
   const addTrustedSender = useSettingsStore((s) => s.addTrustedSender);
   const trustedSendersAddressBook = useSettingsStore((s) => s.trustedSendersAddressBook);
@@ -895,6 +899,10 @@ export function EmailComposer({
   const [autocompleteResults, setAutocompleteResults] = useState<Array<{ name: string; email: string }>>([]);
   const [activeAutoField, setActiveAutoField] = useState<'to' | 'cc' | 'bcc' | null>(null);
   const [autoSelectedIndex, setAutoSelectedIndex] = useState(-1);
+  // Current trimmed query behind the open dropdown, plus the in-flight flag for
+  // the on-demand Sent-folder lookup ("search the server" row).
+  const [autoQuery, setAutoQuery] = useState('');
+  const [isSearchingServer, setIsSearchingServer] = useState(false);
   const autocompleteTimeoutRef = useRef<NodeJS.Timeout | null>(null);
   const toInputRef = useRef<HTMLInputElement>(null);
   const ccInputRef = useRef<HTMLInputElement>(null);
@@ -942,8 +950,10 @@ export function EmailComposer({
       setAutocompleteResults([]);
       setActiveAutoField(null);
       setAutoSelectedIndex(-1);
+      setAutoQuery('');
       return;
     }
+    setAutoQuery(query);
 
     autocompleteTimeoutRef.current = setTimeout(async () => {
       const localResults = getAutocomplete(query);
@@ -951,10 +961,39 @@ export function EmailComposer({
       const initial: RecipientSuggestion[] = localResults.map(r => ({ name: r.name, email: r.email }));
       const merged = await contactHooks.onProvideRecipientSuggestions.transform(initial, { query });
       setAutocompleteResults(merged.map(s => ({ name: s.name, email: s.email })));
-      setActiveAutoField(merged.length > 0 ? field : null);
+      // Keep the dropdown open even without local hits when a server search is
+      // available, so the "search the server" row stays reachable (OWA-style).
+      setActiveAutoField(merged.length > 0 || canSearchServer ? field : null);
       setAutoSelectedIndex(-1);
     }, 200);
-  }, [getAutocomplete]);
+  }, [getAutocomplete, canSearchServer]);
+
+  // On-demand: search the Sent folder server-side for recipients matching the
+  // current query and merge fresh hits into the open dropdown (deduped by email).
+  const handleServerSearch = useCallback(async () => {
+    const query = autoQuery.trim();
+    if (!composerClient || !query || isSearchingServer) return;
+    setIsSearchingServer(true);
+    try {
+      const serverResults = await searchRecipients(composerClient, query);
+      setAutocompleteResults((prev) => {
+        const seen = new Set(prev.map((r) => r.email.toLowerCase()));
+        const merged = [...prev];
+        for (const r of serverResults) {
+          const key = r.email.toLowerCase();
+          if (!seen.has(key)) {
+            seen.add(key);
+            merged.push(r);
+          }
+        }
+        return merged;
+      });
+    } catch {
+      // Best-effort: a failed lookup just leaves the local suggestions in place.
+    } finally {
+      setIsSearchingServer(false);
+    }
+  }, [autoQuery, composerClient, isSearchingServer, searchRecipients]);
 
   const insertAutocomplete = (suggestion: { name: string; email: string }, field: 'to' | 'cc' | 'bcc') => {
     const setter = field === 'to' ? setTo : field === 'cc' ? setCc : setBcc;
@@ -2147,6 +2186,10 @@ export function EmailComposer({
               autoSelectedIndex={autoSelectedIndex}
               dropdownRef={toDropdownRef}
               onInsertAutocomplete={insertAutocomplete}
+              canSearchServer={canSearchServer}
+              onServerSearch={handleServerSearch}
+              isSearchingServer={isSearchingServer}
+              serverSearchQuery={autoQuery}
               validationError={validationErrors.to}
               validationMessage={t('validation.recipient_required')}
               onTab={focusSubject}
@@ -2224,6 +2267,10 @@ export function EmailComposer({
                 autoSelectedIndex={autoSelectedIndex}
                 dropdownRef={ccDropdownRef}
                 onInsertAutocomplete={insertAutocomplete}
+                canSearchServer={canSearchServer}
+                onServerSearch={handleServerSearch}
+                isSearchingServer={isSearchingServer}
+                serverSearchQuery={autoQuery}
                 onMoveChip={handleMoveChip}
               />
             </div>
@@ -2249,6 +2296,10 @@ export function EmailComposer({
                 autoSelectedIndex={autoSelectedIndex}
                 dropdownRef={bccDropdownRef}
                 onInsertAutocomplete={insertAutocomplete}
+                canSearchServer={canSearchServer}
+                onServerSearch={handleServerSearch}
+                isSearchingServer={isSearchingServer}
+                serverSearchQuery={autoQuery}
                 onMoveChip={handleMoveChip}
               />
             </div>
@@ -2670,7 +2721,10 @@ const AutocompleteDropdown = React.forwardRef<HTMLDivElement, {
   results: Array<{ name: string; email: string }>;
   selectedIndex: number;
   onSelect: (suggestion: { name: string; email: string }) => void;
-}>(function AutocompleteDropdown({ id, results, selectedIndex, onSelect }, ref) {
+  onSearchServer?: () => void;
+  isSearchingServer?: boolean;
+}>(function AutocompleteDropdown({ id, results, selectedIndex, onSelect, onSearchServer, isSearchingServer }, ref) {
+  const t = useTranslations('email_composer');
   return (
     <div ref={ref} id={id} role="listbox" className="absolute top-full left-0 right-0 z-50 mt-1 bg-background border border-border rounded-md shadow-lg max-h-48 overflow-y-auto">
       {results.map((r, i) => (
@@ -2696,6 +2750,27 @@ const AutocompleteDropdown = React.forwardRef<HTMLDivElement, {
           )}
         </button>
       ))}
+      {onSearchServer && (
+        <button
+          type="button"
+          disabled={isSearchingServer}
+          className={cn(
+            "w-full px-3 py-2 text-left text-sm flex items-center gap-2 text-muted-foreground hover:bg-muted disabled:opacity-60 disabled:cursor-default",
+            results.length > 0 && "border-t border-border"
+          )}
+          onMouseDown={(e) => {
+            e.preventDefault();
+            if (!isSearchingServer) onSearchServer();
+          }}
+        >
+          {isSearchingServer
+            ? <Loader2 className="w-4 h-4 shrink-0 animate-spin" />
+            : <Search className="w-4 h-4 shrink-0" />}
+          <span className="truncate">
+            {isSearchingServer ? t('autocomplete_searching') : t('autocomplete_search_server')}
+          </span>
+        </button>
+      )}
     </div>
   );
 });
@@ -2716,6 +2791,10 @@ function RecipientChipInput({
   autoSelectedIndex,
   dropdownRef,
   onInsertAutocomplete,
+  canSearchServer,
+  onServerSearch,
+  isSearchingServer,
+  serverSearchQuery,
   validationError,
   validationMessage,
   onTab,
@@ -2736,6 +2815,10 @@ function RecipientChipInput({
   autoSelectedIndex: number;
   dropdownRef: React.RefObject<HTMLDivElement | null>;
   onInsertAutocomplete: (suggestion: { name: string; email: string }, field: 'to' | 'cc' | 'bcc') => void;
+  canSearchServer: boolean;
+  onServerSearch: () => void;
+  isSearchingServer: boolean;
+  serverSearchQuery: string;
   validationError?: boolean;
   validationMessage?: string;
   onTab?: () => void;
@@ -3037,13 +3120,16 @@ function RecipientChipInput({
       {validationError && validationMessage && (
         <p className="text-xs text-red-600 dark:text-red-400 mt-0.5">{validationMessage}</p>
       )}
-      {activeAutoField === field && autocompleteResults.length > 0 && (
+      {activeAutoField === field &&
+        (autocompleteResults.length > 0 || (canSearchServer && serverSearchQuery.length > 0)) && (
         <AutocompleteDropdown
           ref={dropdownRef}
           id={`autocomplete-${field}`}
           results={autocompleteResults}
           selectedIndex={autoSelectedIndex}
           onSelect={(suggestion) => onInsertAutocomplete(suggestion, field)}
+          onSearchServer={canSearchServer && serverSearchQuery.length > 0 ? onServerSearch : undefined}
+          isSearchingServer={isSearchingServer}
         />
       )}
       <ContextMenu

lib/demo/demo-client.ts

@@ -209,6 +209,23 @@ export class DemoJMAPClient implements IJMAPClient {
     return { emails, hasMore: position + limit < total, total };
   }
 
+  async searchSentRecipients(query: string, _sentMailboxId: string, _accountId?: string, _limit: number = 60): Promise<Array<{ name: string; email: string }>> {
+    const q = query.trim().toLowerCase();
+    if (!q) return [];
+    const byEmail = new Map<string, { name: string; email: string }>();
+    for (const email of this.data.emails) {
+      for (const r of [...(email.to || []), ...(email.cc || [])]) {
+        if (!r.email) continue;
+        const key = r.email.toLowerCase();
+        if (byEmail.has(key)) continue;
+        if (key.includes(q) || (r.name && r.name.toLowerCase().includes(q))) {
+          byEmail.set(key, { name: r.name || '', email: r.email });
+        }
+      }
+    }
+    return Array.from(byEmail.values());
+  }
+
   // ── Email mutations ───────────────────────────────────────────
 
   async markAsRead(emailId: string, read: boolean = true): Promise<void> {

lib/jmap/client-interface.ts

@@ -89,6 +89,13 @@ export interface IJMAPClient {
     limit?: number,
     position?: number,
   ): Promise<{ emails: Email[]; hasMore: boolean; total: number }>;
+  /**
+   * Lean recipient search for compose autocomplete ("search the server" action):
+   * finds messages in `sentMailboxId` whose to/cc matches `query` and returns
+   * only the matching addresses (fetches just the `to`/`cc` properties - no
+   * bodies or attachments), deduped.
+   */
+  searchSentRecipients(query: string, sentMailboxId: string, accountId?: string, limit?: number): Promise<Array<{ name: string; email: string }>>;
 
   // ── Email mutations ───────────────────────────────────────────
   markAsRead(emailId: string, read?: boolean, accountId?: string): Promise<void>;

lib/jmap/client.ts

@@ -1887,6 +1887,53 @@ export class JMAPClient implements IJMAPClient {
     }
   }
 
+  async searchSentRecipients(query: string, sentMailboxId: string, accountId?: string, limit: number = 60): Promise<Array<{ name: string; email: string }>> {
+    const q = query.trim();
+    if (!q || !sentMailboxId) return [];
+    try {
+      const targetAccountId = accountId || this.accountId;
+      const response = await this.request([
+        ["Email/query", {
+          accountId: targetAccountId,
+          filter: {
+            operator: "AND",
+            conditions: [
+              { inMailbox: sentMailboxId },
+              { operator: "OR", conditions: [{ to: q }, { cc: q }] },
+            ],
+          },
+          sort: [{ property: "receivedAt", isAscending: false }],
+          limit,
+        }, "0"],
+        // Fetch ONLY the recipient fields - no subject/preview/body/attachments.
+        ["Email/get", {
+          accountId: targetAccountId,
+          "#ids": { resultOf: "0", name: "Email/query", path: "/ids" },
+          properties: ["to", "cc"],
+        }, "1"],
+      ]);
+      const emails = (response.methodResponses?.[1]?.[1]?.list || []) as Email[];
+      const lower = q.toLowerCase();
+      const byEmail = new Map<string, { name: string; email: string }>();
+      for (const email of emails) {
+        for (const r of [...(email.to || []), ...(email.cc || [])]) {
+          if (!r.email) continue;
+          const key = r.email.toLowerCase().trim();
+          if (!key || byEmail.has(key)) continue;
+          // The query matched *some* recipient of the message; keep only the
+          // addresses that actually match, not every co-recipient.
+          if (key.includes(lower) || (r.name && r.name.toLowerCase().includes(lower))) {
+            byEmail.set(key, { name: (r.name || "").trim(), email: r.email });
+          }
+        }
+      }
+      return Array.from(byEmail.values());
+    } catch (error) {
+      console.error('Recipient search failed:', error);
+      return [];
+    }
+  }
+
   async getThread(threadId: string, accountId?: string): Promise<Thread | null> {
     try {
       const targetAccountId = accountId || this.accountId;

locales/cs/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "Upravit e-mailovou adresu",
     "recipient_edit_name": "Upravit zobrazované jméno",
     "recipient_email_placeholder": "E-mailová adresa",
-    "recipient_name_placeholder": "Zobrazované jméno"
+    "recipient_name_placeholder": "Zobrazované jméno",
+    "autocomplete_search_server": "Hledat na serveru",
+    "autocomplete_searching": "Hledání..."
   },
   "confirm_dialog": {
     "confirm": "Potvrdit",

locales/da/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "Rediger e-mailadresse",
     "recipient_edit_name": "Rediger visningsnavn",
     "recipient_email_placeholder": "E-mailadresse",
-    "recipient_name_placeholder": "Visningsnavn"
+    "recipient_name_placeholder": "Visningsnavn",
+    "autocomplete_search_server": "Søg på serveren",
+    "autocomplete_searching": "Søger..."
   },
   "confirm_dialog": {
     "confirm": "Bekræft",

locales/de/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "E-Mail-Adresse bearbeiten",
     "recipient_edit_name": "Anzeigenamen bearbeiten",
     "recipient_email_placeholder": "E-Mail-Adresse",
-    "recipient_name_placeholder": "Anzeigename"
+    "recipient_name_placeholder": "Anzeigename",
+    "autocomplete_search_server": "Auf dem Server suchen",
+    "autocomplete_searching": "Suche läuft..."
   },
   "confirm_dialog": {
     "confirm": "Bestätigen",

locales/en/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "Edit email address",
     "recipient_edit_name": "Edit display name",
     "recipient_email_placeholder": "Email address",
-    "recipient_name_placeholder": "Display name"
+    "recipient_name_placeholder": "Display name",
+    "autocomplete_search_server": "Search the server",
+    "autocomplete_searching": "Searching..."
   },
   "confirm_dialog": {
     "confirm": "Confirm",

locales/es/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "Editar dirección de correo",
     "recipient_edit_name": "Editar nombre para mostrar",
     "recipient_email_placeholder": "Dirección de correo",
-    "recipient_name_placeholder": "Nombre para mostrar"
+    "recipient_name_placeholder": "Nombre para mostrar",
+    "autocomplete_search_server": "Buscar en el servidor",
+    "autocomplete_searching": "Buscando..."
   },
   "confirm_dialog": {
     "confirm": "Confirmar",

locales/fa/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "ویرایش آدرس ایمیل",
     "recipient_edit_name": "ویرایش نام نمایشی",
     "recipient_email_placeholder": "آدرس ایمیل",
-    "recipient_name_placeholder": "نام نمایشی"
+    "recipient_name_placeholder": "نام نمایشی",
+    "autocomplete_search_server": "جستجو در سرور",
+    "autocomplete_searching": "در حال جستجو..."
   },
   "confirm_dialog": {
     "confirm": "تأیید",

locales/fr/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "Modifier l'adresse e-mail",
     "recipient_edit_name": "Modifier le nom d'affichage",
     "recipient_email_placeholder": "Adresse e-mail",
-    "recipient_name_placeholder": "Nom d'affichage"
+    "recipient_name_placeholder": "Nom d'affichage",
+    "autocomplete_search_server": "Rechercher sur le serveur",
+    "autocomplete_searching": "Recherche en cours..."
   },
   "confirm_dialog": {
     "confirm": "Confirmer",

locales/hu/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "E-mail-cím szerkesztése",
     "recipient_edit_name": "Megjelenített név szerkesztése",
     "recipient_email_placeholder": "E-mail-cím",
-    "recipient_name_placeholder": "Megjelenített név"
+    "recipient_name_placeholder": "Megjelenített név",
+    "autocomplete_search_server": "Keresés a kiszolgálón",
+    "autocomplete_searching": "Keresés..."
   },
   "confirm_dialog": {
     "confirm": "Megerősítés",

locales/it/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "Modifica indirizzo email",
     "recipient_edit_name": "Modifica nome visualizzato",
     "recipient_email_placeholder": "Indirizzo email",
-    "recipient_name_placeholder": "Nome visualizzato"
+    "recipient_name_placeholder": "Nome visualizzato",
+    "autocomplete_search_server": "Cerca nel server",
+    "autocomplete_searching": "Ricerca in corso..."
   },
   "confirm_dialog": {
     "confirm": "Conferma",

locales/ja/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "メールアドレスを編集",
     "recipient_edit_name": "表示名を編集",
     "recipient_email_placeholder": "メールアドレス",
-    "recipient_name_placeholder": "表示名"
+    "recipient_name_placeholder": "表示名",
+    "autocomplete_search_server": "サーバーを検索",
+    "autocomplete_searching": "検索中..."
   },
   "confirm_dialog": {
     "confirm": "確認",

locales/ko/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "이메일 주소 편집",
     "recipient_edit_name": "표시 이름 편집",
     "recipient_email_placeholder": "이메일 주소",
-    "recipient_name_placeholder": "표시 이름"
+    "recipient_name_placeholder": "표시 이름",
+    "autocomplete_search_server": "서버에서 검색",
+    "autocomplete_searching": "검색 중..."
   },
   "confirm_dialog": {
     "confirm": "확인",

locales/lv/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "Rediģēt e-pasta adresi",
     "recipient_edit_name": "Rediģēt parādāmo vārdu",
     "recipient_email_placeholder": "E-pasta adrese",
-    "recipient_name_placeholder": "Parādāmais vārds"
+    "recipient_name_placeholder": "Parādāmais vārds",
+    "autocomplete_search_server": "Meklēt serverī",
+    "autocomplete_searching": "Meklē..."
   },
   "confirm_dialog": {
     "confirm": "Apstiprināt",

locales/nl/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "E-mailadres bewerken",
     "recipient_edit_name": "Weergavenaam bewerken",
     "recipient_email_placeholder": "E-mailadres",
-    "recipient_name_placeholder": "Weergavenaam"
+    "recipient_name_placeholder": "Weergavenaam",
+    "autocomplete_search_server": "Op de server zoeken",
+    "autocomplete_searching": "Bezig met zoeken..."
   },
   "confirm_dialog": {
     "confirm": "Bevestigen",

locales/pl/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "Edytuj adres e-mail",
     "recipient_edit_name": "Edytuj wyświetlaną nazwę",
     "recipient_email_placeholder": "Adres e-mail",
-    "recipient_name_placeholder": "Wyświetlana nazwa"
+    "recipient_name_placeholder": "Wyświetlana nazwa",
+    "autocomplete_search_server": "Szukaj na serwerze",
+    "autocomplete_searching": "Wyszukiwanie..."
   },
   "confirm_dialog": {
     "confirm": "Potwierdź",

locales/pt/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "Editar endereço de e-mail",
     "recipient_edit_name": "Editar nome de exibição",
     "recipient_email_placeholder": "Endereço de e-mail",
-    "recipient_name_placeholder": "Nome de exibição"
+    "recipient_name_placeholder": "Nome de exibição",
+    "autocomplete_search_server": "Pesquisar no servidor",
+    "autocomplete_searching": "Pesquisando..."
   },
   "confirm_dialog": {
     "confirm": "Confirmar",

locales/ro/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "Editați adresa de e-mail",
     "recipient_edit_name": "Editați numele afișat",
     "recipient_email_placeholder": "Adresă de e-mail",
-    "recipient_name_placeholder": "Numele afișat"
+    "recipient_name_placeholder": "Numele afișat",
+    "autocomplete_search_server": "Caută pe server",
+    "autocomplete_searching": "Se caută..."
   },
   "confirm_dialog": {
     "confirm": "Confirmare",

locales/ru/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "Изменить адрес эл. почты",
     "recipient_edit_name": "Изменить отображаемое имя",
     "recipient_email_placeholder": "Адрес эл. почты",
-    "recipient_name_placeholder": "Отображаемое имя"
+    "recipient_name_placeholder": "Отображаемое имя",
+    "autocomplete_search_server": "Искать на сервере",
+    "autocomplete_searching": "Поиск..."
   },
   "confirm_dialog": {
     "confirm": "Подтвердить",

locales/tr/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "E-posta adresini düzenle",
     "recipient_edit_name": "Görünen adı düzenle",
     "recipient_email_placeholder": "E-posta adresi",
-    "recipient_name_placeholder": "Görünen ad"
+    "recipient_name_placeholder": "Görünen ad",
+    "autocomplete_search_server": "Sunucuda ara",
+    "autocomplete_searching": "Aranıyor..."
   },
   "confirm_dialog": {
     "confirm": "Onayla",

locales/uk/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "Змінити адресу ел. пошти",
     "recipient_edit_name": "Змінити відображуване ім'я",
     "recipient_email_placeholder": "Адреса ел. пошти",
-    "recipient_name_placeholder": "Відображуване ім'я"
+    "recipient_name_placeholder": "Відображуване ім'я",
+    "autocomplete_search_server": "Шукати на сервері",
+    "autocomplete_searching": "Пошук..."
   },
   "confirm_dialog": {
     "confirm": "Підтвердити",

locales/zh/common.json

@@ -677,7 +677,9 @@
     "recipient_edit_email": "编辑电子邮件地址",
     "recipient_edit_name": "编辑显示名称",
     "recipient_email_placeholder": "电子邮件地址",
-    "recipient_name_placeholder": "显示名称"
+    "recipient_name_placeholder": "显示名称",
+    "autocomplete_search_server": "在服务器上搜索",
+    "autocomplete_searching": "搜索中..."
   },
   "confirm_dialog": {
     "confirm": "确认",

stores/contact-store.ts

@@ -155,6 +155,11 @@ interface ContactStore {
   trustedSendersLoaded: boolean;
   trustedSendersLoading: boolean;
 
+  // Recent recipients (from the Sent folder) for compose autocomplete - runtime only
+  recentRecipients: Array<{ name: string; email: string }>;
+  recentRecipientsLoaded: boolean;
+  sentMailboxId: string | null;
+
   selectedContactIds: Set<string>;
   lastSelectedContactId: string | null;
   activeTab: 'all' | 'groups';
@@ -214,6 +219,11 @@ interface ContactStore {
   addToTrustedSendersBook: (client: IJMAPClient, email: string) => Promise<void>;
   removeFromTrustedSendersBook: (client: IJMAPClient, email: string) => Promise<void>;
   isTrustedAddressBookSender: (email: string) => boolean;
+
+  // Recent recipients (compose autocomplete, derived from the Sent folder)
+  loadRecentRecipients: (client: IJMAPClient, sentMailboxId: string) => Promise<void>;
+  // On-demand "search the server" for recipients not in the recent cache
+  searchRecipients: (client: IJMAPClient, query: string) => Promise<Array<{ name: string; email: string }>>;
 }
 
 export const useContactStore = create<ContactStore>()(
@@ -262,6 +272,9 @@ export const useContactStore = create<ContactStore>()(
       trustedSendersBookId: null,
       trustedSendersLoaded: false,
       trustedSendersLoading: false,
+      recentRecipients: [],
+      recentRecipientsLoaded: false,
+      sentMailboxId: null,
       selectedContactIds: new Set<string>(),
       lastSelectedContactId: null,
       activeTab: 'all' as const,
@@ -576,6 +589,25 @@ export const useContactStore = create<ContactStore>()(
           }
         }
 
+        // Finally fold in recent recipients from the Sent folder (people you've
+        // written to - the OWA-style autocomplete cache). Contacts and directory
+        // principals take precedence, so skip any address already suggested (no
+        // duplicates). These carry the display name from the message, so match
+        // on name or address.
+        const { recentRecipients } = get();
+        if (recentRecipients.length > 0 && results.length < 10) {
+          const seenRecent = new Set(results.map(r => r.email.toLowerCase()));
+          for (const rec of recentRecipients) {
+            if (results.length >= 10) break;
+            const addr = rec.email.toLowerCase();
+            if (seenRecent.has(addr)) continue;
+            if (addr.includes(lower) || (rec.name && rec.name.toLowerCase().includes(lower))) {
+              results.push({ name: rec.name, email: rec.email });
+              seenRecent.add(addr);
+            }
+          }
+        }
+
         return results;
       },
 
@@ -959,6 +991,44 @@ export const useContactStore = create<ContactStore>()(
         }
       },
 
+      loadRecentRecipients: async (client, sentMailboxId) => {
+        if (sentMailboxId) set({ sentMailboxId });
+        if (get().recentRecipientsLoaded || !sentMailboxId) return;
+        try {
+          // Read the Sent folder and collect the people we've written to, so
+          // compose autocomplete can suggest them (OWA-style). getEmails sorts
+          // receivedAt desc, so keeping the first occurrence per address yields
+          // the most recent one plus its display name.
+          const { emails } = await client.getEmails(sentMailboxId, undefined, 300, 0);
+          const byEmail = new Map<string, { name: string; email: string }>();
+          for (const email of emails) {
+            for (const r of [...(email.to || []), ...(email.cc || [])]) {
+              if (!r.email) continue;
+              const key = r.email.toLowerCase().trim();
+              if (!key || byEmail.has(key)) continue;
+              byEmail.set(key, { name: (r.name || '').trim(), email: r.email });
+            }
+          }
+          set({ recentRecipients: Array.from(byEmail.values()), recentRecipientsLoaded: true });
+          debug.log('contacts', 'Loaded', byEmail.size, 'recent recipients from Sent');
+        } catch (error) {
+          debug.error('Failed to load recent recipients:', error);
+          set({ recentRecipientsLoaded: true });
+        }
+      },
+
+      searchRecipients: async (client, query) => {
+        const { sentMailboxId } = get();
+        const q = query.trim();
+        if (!sentMailboxId || q.length < 1) return [];
+        try {
+          return await client.searchSentRecipients(q, sentMailboxId);
+        } catch (error) {
+          debug.error('Recipient server search failed:', error);
+          return [];
+        }
+      },
+
       loadTrustedSendersBook: async (client) => {
         if (get().trustedSendersLoading) return;
         set({ trustedSendersLoading: true });