diff --git a/apps/api/internal/app/app_test.go b/apps/api/internal/app/app_test.go
index e5c391f..3db4aaa 100644
--- a/apps/api/internal/app/app_test.go
+++ b/apps/api/internal/app/app_test.go
@@ -2632,6 +2632,162 @@ func TestMessageFlagsUpdateMaildir(t *testing.T) {
 	}
 }
 
+func TestMaildirSyncUpdatesMovedMessageState(t *testing.T) {
+	a := newTestApp(t)
+	ctx := context.Background()
+	a.cfg.MaildirRoot = t.TempDir()
+	user, mb := defaultAdminUserAndMailbox(t, a)
+	clearMailboxMessagesForTest(t, a, mb.ID)
+
+	msg, err := a.sendMailNow(ctx, user, mb, mailComposeInput{
+		MailboxID: mb.ID,
+		To:        []string{"recipient@example.test"},
+		Subject:   "imap moved",
+		Text:      "move body",
+		HTML:      "<p>move body</p>",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	sentPath := maildirRawPathForTest(t, a, msg.ID)
+	archiveID, err := a.ensureFolder(ctx, mb.ID, "Archive")
+	if err != nil {
+		t.Fatal(err)
+	}
+	archiveDir := filepath.Join(filepath.Dir(filepath.Dir(filepath.Dir(sentPath))), ".Archive", "cur")
+	if err := os.MkdirAll(archiveDir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	archivePath := filepath.Join(archiveDir, filepath.Base(sentPath))
+	if err := os.Rename(sentPath, archivePath); err != nil {
+		t.Fatal(err)
+	}
+	count, err := a.syncMaildirOnce(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if count != 0 {
+		t.Fatalf("sync count=%d, want no import/backfill", count)
+	}
+	var folderID, rawPath string
+	if err := a.db.QueryRowContext(ctx, `SELECT folder_id,raw_path FROM messages WHERE id=?`, msg.ID).Scan(&folderID, &rawPath); err != nil {
+		t.Fatal(err)
+	}
+	if folderID != archiveID || rawPath != archivePath {
+		t.Fatalf("folder/raw after move=%q %q, want %q %q", folderID, rawPath, archiveID, archivePath)
+	}
+}
+
+func TestMaildirSyncKeepsDistinctCopiesWithSameMessageID(t *testing.T) {
+	a := newTestApp(t)
+	ctx := context.Background()
+	a.cfg.MaildirRoot = t.TempDir()
+	user, mb := defaultAdminUserAndMailbox(t, a)
+	clearMailboxMessagesForTest(t, a, mb.ID)
+
+	msg, err := a.sendMailNow(ctx, user, mb, mailComposeInput{
+		MailboxID: mb.ID,
+		To:        []string{"admin@lanqin.local"},
+		Subject:   "self copy",
+		Text:      "self body",
+		HTML:      "<p>self body</p>",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := a.syncMaildirOnce(ctx); err != nil {
+		t.Fatal(err)
+	}
+	var copies int
+	if err := a.db.QueryRowContext(ctx, `SELECT COUNT(*) FROM messages WHERE mailbox_id=? AND message_id=?`, mb.ID, msg.MessageID).Scan(&copies); err != nil {
+		t.Fatal(err)
+	}
+	if copies != 2 {
+		t.Fatalf("copies with same Message-ID=%d, want Sent and Inbox copies", copies)
+	}
+}
+
+func TestMaildirSyncUpdatesFlagsFromIMAP(t *testing.T) {
+	a := newTestApp(t)
+	ctx := context.Background()
+	a.cfg.MaildirRoot = t.TempDir()
+	user, mb := defaultAdminUserAndMailbox(t, a)
+	clearMailboxMessagesForTest(t, a, mb.ID)
+
+	msg, err := a.sendMailNow(ctx, user, mb, mailComposeInput{
+		MailboxID: mb.ID,
+		To:        []string{"recipient@example.test"},
+		Subject:   "imap flags",
+		Text:      "flag body",
+		HTML:      "<p>flag body</p>",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	rawPath := maildirRawPathForTest(t, a, msg.ID)
+	flaggedPath := maildirPathWithFlags(rawPath, false, true)
+	if err := os.MkdirAll(filepath.Dir(flaggedPath), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Rename(rawPath, flaggedPath); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := a.db.ExecContext(ctx, `UPDATE messages SET updated_at=? WHERE id=?`, a.now().UTC().Add(-10*time.Minute).Format(time.RFC3339Nano), msg.ID); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := a.syncMaildirOnce(ctx); err != nil {
+		t.Fatal(err)
+	}
+	var read, starred int
+	var dbPath string
+	if err := a.db.QueryRowContext(ctx, `SELECT is_read,is_starred,raw_path FROM messages WHERE id=?`, msg.ID).Scan(&read, &starred, &dbPath); err != nil {
+		t.Fatal(err)
+	}
+	if read != 0 || starred != 1 || dbPath != flaggedPath {
+		t.Fatalf("flags/path after sync read=%d starred=%d path=%q want 0 1 %q", read, starred, dbPath, flaggedPath)
+	}
+}
+
+func TestMaildirSyncDeletesMissingMessage(t *testing.T) {
+	a := newTestApp(t)
+	ctx := context.Background()
+	a.cfg.MaildirRoot = t.TempDir()
+	user, mb := defaultAdminUserAndMailbox(t, a)
+	clearMailboxMessagesForTest(t, a, mb.ID)
+
+	msg, err := a.sendMailNow(ctx, user, mb, mailComposeInput{
+		MailboxID: mb.ID,
+		To:        []string{"recipient@example.test"},
+		Subject:   "imap delete",
+		Text:      "delete body",
+		HTML:      "<p>delete body</p>",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	rawPath := maildirRawPathForTest(t, a, msg.ID)
+	if err := os.Remove(rawPath); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := a.db.ExecContext(ctx, `UPDATE messages SET updated_at=? WHERE id=?`, a.now().UTC().Add(-10*time.Minute).Format(time.RFC3339Nano), msg.ID); err != nil {
+		t.Fatal(err)
+	}
+	count, err := a.syncMaildirOnce(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if count != 1 {
+		t.Fatalf("cleanup count=%d, want 1", count)
+	}
+	var remaining int
+	if err := a.db.QueryRowContext(ctx, `SELECT COUNT(*) FROM messages WHERE id=?`, msg.ID).Scan(&remaining); err != nil {
+		t.Fatal(err)
+	}
+	if remaining != 0 {
+		t.Fatalf("message remaining=%d, want deleted", remaining)
+	}
+}
+
 func mustDefaultDomainID(t *testing.T, a *App) string {
 	t.Helper()
 	var id string
diff --git a/apps/api/internal/app/maildir_sync.go b/apps/api/internal/app/maildir_sync.go
index 36e591a..c7bf78f 100644
--- a/apps/api/internal/app/maildir_sync.go
+++ b/apps/api/internal/app/maildir_sync.go
@@ -137,6 +137,11 @@ func (a *App) syncMaildirOnce(ctx context.Context) (int, error) {
 		return imported, err
 	}
 	imported += backfilled
+	cleaned, err := a.cleanupMissingMaildirMessages(ctx)
+	if err != nil {
+		return imported, err
+	}
+	imported += cleaned
 	return imported, nil
 }
 
@@ -297,7 +302,7 @@ func (a *App) syncMaildirFile(ctx context.Context, mb maildirMailbox, folder mai
 	}
 	msg.MailboxID = mb.ID
 	msg.FolderID = folder.ID
-	msg.IsRead = !strings.EqualFold(folder.Name, "Inbox")
+	msg.IsRead, msg.IsStarred = maildirFlagsFromPath(path, folder.Name)
 	msg.RawPath = path
 	if msg.MessageUID == "" {
 		msg.MessageUID = newID("uid")
@@ -317,7 +322,14 @@ func (a *App) syncMaildirFile(ctx context.Context, mb maildirMailbox, folder mai
 	if exists, err := a.maildirMessageExists(ctx, mb.ID, folder.ID, path, msg.MessageID); err != nil {
 		return false, err
 	} else if exists {
-		a.attachMaildirRawPathToExisting(ctx, mb.ID, folder.ID, path, msg.MessageID)
+		if _, err := a.syncExistingMaildirMessageState(ctx, mb.ID, folder.ID, path, msg.MessageID, msg.IsRead, msg.IsStarred); err != nil {
+			return false, err
+		}
+		return false, nil
+	}
+	if handled, err := a.syncExistingMaildirMessageState(ctx, mb.ID, folder.ID, path, msg.MessageID, msg.IsRead, msg.IsStarred); err != nil {
+		return false, err
+	} else if handled {
 		return false, nil
 	}
 	id, err := a.insertMessage(ctx, msg, attachments)
@@ -355,6 +367,145 @@ func (a *App) attachMaildirRawPathToExisting(ctx context.Context, mailboxID, fol
 	}
 }
 
+func (a *App) syncExistingMaildirMessageState(ctx context.Context, mailboxID, folderID, rawPath, messageID string, read, starred bool) (bool, error) {
+	now := a.now().UTC().Format(time.RFC3339Nano)
+	res, err := a.db.ExecContext(ctx, `UPDATE messages SET folder_id=?,raw_path=?,is_read=?,is_starred=?,updated_at=? WHERE mailbox_id=? AND raw_path=?`,
+		folderID, rawPath, boolInt(read), boolInt(starred), now, mailboxID, rawPath)
+	if err != nil {
+		return false, err
+	}
+	if rows, _ := res.RowsAffected(); rows > 0 {
+		return true, nil
+	}
+	if strings.TrimSpace(messageID) == "" {
+		return false, nil
+	}
+	type candidate struct {
+		ID      string
+		RawPath string
+	}
+	rows, err := a.db.QueryContext(ctx, `SELECT id,raw_path FROM messages WHERE mailbox_id=? AND message_id=? AND message_id <> '' ORDER BY CASE WHEN folder_id=? THEN 0 ELSE 1 END, created_at`, mailboxID, messageID, folderID)
+	if err != nil {
+		return false, err
+	}
+	var chosen candidate
+	for rows.Next() {
+		var c candidate
+		if err := rows.Scan(&c.ID, &c.RawPath); err != nil {
+			rows.Close()
+			return false, err
+		}
+		if c.RawPath == "" || c.RawPath == rawPath {
+			chosen = c
+			break
+		}
+		ok, err := a.pathIsUnderMaildirRoot(c.RawPath)
+		if err != nil {
+			rows.Close()
+			return false, err
+		}
+		if ok {
+			if _, err := os.Stat(c.RawPath); errors.Is(err, os.ErrNotExist) {
+				chosen = c
+				break
+			} else if err != nil {
+				rows.Close()
+				return false, err
+			}
+		}
+	}
+	if err := rows.Err(); err != nil {
+		rows.Close()
+		return false, err
+	}
+	if err := rows.Close(); err != nil {
+		return false, err
+	}
+	if chosen.ID == "" {
+		a.removeDuplicateMaildirMessage(ctx, rawPath, mailboxID, folderID, messageID)
+		return false, nil
+	}
+	_, err = a.db.ExecContext(ctx, `UPDATE messages SET folder_id=?,raw_path=?,is_read=?,is_starred=?,updated_at=? WHERE id=?`, folderID, rawPath, boolInt(read), boolInt(starred), now, chosen.ID)
+	return err == nil, err
+}
+
+func (a *App) removeDuplicateMaildirMessage(ctx context.Context, rawPath, mailboxID, folderID, messageID string) {
+	var existing string
+	err := a.db.QueryRowContext(ctx, `SELECT raw_path FROM messages WHERE mailbox_id=? AND folder_id=? AND message_id=? AND message_id <> '' AND raw_path<>'' LIMIT 1`, mailboxID, folderID, messageID).Scan(&existing)
+	if err != nil || existing == "" || existing == rawPath {
+		return
+	}
+	a.removeMaildirPath(ctx, rawPath)
+}
+
+func (a *App) cleanupMissingMaildirMessages(ctx context.Context) (int, error) {
+	if strings.TrimSpace(a.cfg.MaildirRoot) == "" {
+		return 0, nil
+	}
+	cutoff := a.now().UTC().Add(-5 * time.Minute).Format(time.RFC3339Nano)
+	rows, err := a.db.QueryContext(ctx, `SELECT id,raw_path FROM messages WHERE COALESCE(mailbox_id,'')<>'' AND raw_path<>'' AND updated_at<?`, cutoff)
+	if err != nil {
+		return 0, err
+	}
+	type item struct {
+		ID      string
+		RawPath string
+	}
+	var missing []item
+	for rows.Next() {
+		var it item
+		if err := rows.Scan(&it.ID, &it.RawPath); err != nil {
+			rows.Close()
+			return 0, err
+		}
+		ok, err := a.pathIsUnderMaildirRoot(it.RawPath)
+		if err != nil {
+			rows.Close()
+			return 0, err
+		}
+		if !ok {
+			continue
+		}
+		if _, err := os.Stat(it.RawPath); errors.Is(err, os.ErrNotExist) {
+			missing = append(missing, it)
+		} else if err != nil {
+			rows.Close()
+			return 0, err
+		}
+	}
+	if err := rows.Err(); err != nil {
+		rows.Close()
+		return 0, err
+	}
+	if err := rows.Close(); err != nil {
+		return 0, err
+	}
+	for _, it := range missing {
+		a.deleteMessageFiles(ctx, it.ID)
+		if _, err := a.db.ExecContext(ctx, `DELETE FROM messages WHERE id=?`, it.ID); err != nil {
+			return 0, err
+		}
+	}
+	return len(missing), nil
+}
+
+func maildirFlagsFromPath(path, folderName string) (bool, bool) {
+	base := filepath.Base(path)
+	flags := ""
+	hasFlags := false
+	for _, sep := range []string{maildirFlagSeparator(), ":2,", "!2,"} {
+		if idx := strings.LastIndex(base, sep); idx >= 0 {
+			flags = base[idx+len(sep):]
+			hasFlags = true
+			break
+		}
+	}
+	if hasFlags {
+		return strings.ContainsRune(flags, 'S'), strings.ContainsRune(flags, 'F')
+	}
+	return !strings.EqualFold(folderName, "Inbox"), false
+}
+
 func (a *App) attachUnregisteredMaildirRawPathToExisting(ctx context.Context, rawPath, messageID, recipient string) {
 	if strings.TrimSpace(messageID) == "" || strings.TrimSpace(rawPath) == "" {
 		return