fix(email): fail-fast IMAP timeouts + manual 'Check now' poll

- Root cause of the 502s: ImapFlow had no connect timeout, so a wrong host/port
  (e.g. IMAP on an SMTP port) hung the request until the proxy returned 502 with
  no message. Added connectionTimeout/greetingTimeout/socketTimeout + a hard
  connectWithTimeout() race on every IMAP client (detect/test/roundtrip/poll).
- Error routes now return 422 with the underlying reason (was 502, which
  collided with the proxy's own 502 and hid the message).
- New 'Check now' button + POST /incoming-config/poll runs the poller on demand
  (respects the incomingMail flag) and reports disabled/unconfigured/busy or N
  ingested — so 'nothing in Received' is diagnosable without waiting 60s.
- en/de strings

backend/src/routes/adminEmail.js

@@ -193,7 +193,7 @@ router.post('/incoming-config/folders', adminAuth, requirePermission('email.view
     res.json({ folders });
   } catch (error) {
     console.error('IMAP folder detection error:', error);
-    res.status(502).json({ error: 'Could not connect to the mailbox. Check host, port and credentials.' });
+    res.status(422).json({ error: `Could not connect to the mailbox (${error.message}). Check host, port (IMAP is usually 993) and credentials.` });
   }
 });
 
@@ -218,7 +218,7 @@ router.post('/incoming-config/test', adminAuth, requirePermission('email.view'),
     res.json(result);
   } catch (error) {
     console.error('IMAP connection test error:', error);
-    res.status(502).json({ error: 'Could not connect to the mailbox. Check host, port, credentials and folder.' });
+    res.status(422).json({ error: `Could not connect to the mailbox (${error.message}). Check host, port (IMAP is usually 993), credentials and folder.` });
   }
 });
 
@@ -240,7 +240,21 @@ router.post('/incoming-config/roundtrip', adminAuth, requirePermission('email.se
       .json({ error: map[result.reason] || 'Round-trip test failed.', sent: !!result.sent, recipient: result.recipient });
   } catch (error) {
     console.error('Round-trip test error:', error);
-    res.status(502).json({ error: 'Round-trip test failed — check both SMTP and IMAP settings.' });
+    res.status(422).json({ error: `Round-trip test failed (${error.message}) — check both SMTP and IMAP settings.` });
+  }
+});
+
+// Run the incoming-mail poller on demand (instead of waiting for the 60s loop)
+// so the admin can verify ingestion + see why nothing arrived. Respects the
+// incomingMail flag — a manual run still won't ingest when the feature is off.
+router.post('/incoming-config/poll', adminAuth, requirePermission('email.view'), async (req, res) => {
+  try {
+    const emailIntakeService = require('../services/emailIntakeService');
+    const result = await emailIntakeService.pollOnce();
+    res.json(result); // { processed } or { skipped: 'disabled'|'unconfigured'|'busy' }
+  } catch (error) {
+    console.error('Manual poll error:', error);
+    res.status(422).json({ error: `Mailbox poll failed (${error.message}).` });
   }
 });
 

backend/src/services/emailIntakeService.js

@@ -20,6 +20,31 @@ const expenseService = require('./expenseService');
 const ALLOWED_MIME = ['application/pdf', 'image/jpeg', 'image/png'];
 let polling = false;
 
+// Fail fast instead of hanging on a wrong host/port (e.g. IMAP pointed at an
+// SMTP port). Without these, ImapFlow waits indefinitely and the HTTP request
+// dies at the proxy as a 502 with no useful message.
+const IMAP_TIMEOUTS = { connectionTimeout: 10000, greetingTimeout: 10000, socketTimeout: 30000 };
+
+function makeImapClient(cfg) {
+  return new ImapFlow({ host: cfg.host, port: cfg.port, secure: cfg.secure, auth: cfg.auth, logger: false, ...IMAP_TIMEOUTS });
+}
+
+/** Connect with a hard ceiling, so a stuck TLS handshake can't hang forever. */
+async function connectWithTimeout(client, ms = 12000) {
+  let timer;
+  const timeout = new Promise((_, reject) => { timer = setTimeout(() => reject(new Error('IMAP connection timed out')), ms); });
+  try {
+    await Promise.race([client.connect(), timeout]);
+  } catch (err) {
+    // Best-effort teardown if connect lost the race but is still pending.
+    try { await client.logout(); } catch (_) { /* noop */ }
+    try { client.close(); } catch (_) { /* noop */ }
+    throw err;
+  } finally {
+    clearTimeout(timer);
+  }
+}
+
 async function isEnabled() {
   const flag = await db('feature_flags').where({ key: 'incomingMail' }).first();
   return !!(flag && (flag.value === true || flag.value === 1 || flag.value === '1'));
@@ -73,8 +98,8 @@ async function listFolders(override) {
     cfg = await getImapConfig();
   }
   if (!cfg) return [];
-  const client = new ImapFlow({ host: cfg.host, port: cfg.port, secure: cfg.secure, auth: cfg.auth, logger: false });
-  await client.connect();
+  const client = makeImapClient(cfg);
+  await connectWithTimeout(client);
   try {
     const list = await client.list();
     return (list || []).map((m) => ({ path: m.path, name: m.name, specialUse: m.specialUse || null }));
@@ -110,8 +135,8 @@ async function testConnection(override) {
     cfg = { host: c.host, port: c.port, secure: c.secure, auth: c.auth };
     folder = c.folder;
   }
-  const client = new ImapFlow({ host: cfg.host, port: cfg.port, secure: cfg.secure, auth: cfg.auth, logger: false });
-  await client.connect();
+  const client = makeImapClient(cfg);
+  await connectWithTimeout(client);
   try {
     const status = await client.status(folder, { messages: true, unseen: true });
     return { ok: true, folder, messages: status.messages || 0, unseen: status.unseen || 0 };
@@ -169,8 +194,8 @@ async function roundTripTest({ timeoutMs = 30000, intervalMs = 3000 } = {}) {
   // 2) Poll IMAP for the tagged message until timeout.
   const cfg = await getImapConfig();
   const folder = cfg?.folder || 'INBOX';
-  const client = new ImapFlow({ host: cfg.host, port: cfg.port, secure: cfg.secure, auth: cfg.auth, logger: false });
-  await client.connect();
+  const client = makeImapClient(cfg);
+  await connectWithTimeout(client);
   const started = Date.now();
   try {
     // eslint-disable-next-line no-constant-condition
@@ -204,10 +229,10 @@ async function pollOnce() {
   if (!cfg) return { skipped: 'unconfigured' };
 
   polling = true;
-  const client = new ImapFlow({ host: cfg.host, port: cfg.port, secure: cfg.secure, auth: cfg.auth, logger: false });
+  const client = makeImapClient(cfg);
   let processed = 0;
   try {
-    await client.connect();
+    await connectWithTimeout(client);
     const lock = await client.getMailboxLock(cfg.folder);
     try {
       // eslint-disable-next-line no-restricted-syntax

frontend/src/components/admin/IncomingMailConfigCard.tsx

@@ -11,7 +11,7 @@ import React, { useEffect, useState } from 'react';
 import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
 import { useTranslation } from 'react-i18next';
 import { toast } from 'react-toastify';
-import { Save, Server, User, Lock, Eye, EyeOff, FolderSearch, PlugZap, Mailbox } from 'lucide-react';
+import { Save, Server, User, Lock, Eye, EyeOff, FolderSearch, PlugZap, Mailbox, RefreshCw } from 'lucide-react';
 import { Button, Card, Input, Loading } from '../common';
 import { emailService, type IncomingMailConfig, type ImapFolder } from '../../services/email.service';
 
@@ -56,6 +56,23 @@ export const IncomingMailConfigCard: React.FC = () => {
     onError: (e: any) => toast.error(e?.response?.data?.error || e.message || t('email.incoming.roundTripFailed', 'Round-trip test failed.')),
   });
 
+  const poll = useMutation({
+    mutationFn: () => emailService.pollIncoming(),
+    onSuccess: (r) => {
+      if (r.skipped === 'disabled') {
+        toast.info(t('email.incoming.pollDisabled', 'Incoming mail is turned off — enable it under Settings → Features.'));
+      } else if (r.skipped === 'unconfigured') {
+        toast.info(t('email.incoming.pollUnconfigured', 'Save the incoming mail settings first.'));
+      } else if (r.skipped === 'busy') {
+        toast.info(t('email.incoming.pollBusy', 'A poll is already running — try again in a moment.'));
+      } else {
+        toast.success(t('email.incoming.pollOk', 'Checked mailbox — {{count}} new email(s) ingested.', { count: r.processed || 0 }));
+        qc.invalidateQueries({ queryKey: ['received-emails'] });
+      }
+    },
+    onError: (e: any) => toast.error(e?.response?.data?.error || e.message || t('email.incoming.pollFailed', 'Mailbox poll failed.')),
+  });
+
   const detect = useMutation({
     mutationFn: () => emailService.listIncomingFolders(cfg),
     onSuccess: (list) => {
@@ -186,6 +203,17 @@ export const IncomingMailConfigCard: React.FC = () => {
           >
             {t('email.incoming.roundTrip', 'Round-trip test')}
           </Button>
+          <Button
+            variant="outline"
+            onClick={() => poll.mutate()}
+            isLoading={poll.isPending}
+            disabled={!cfg.imap_host || !cfg.imap_user}
+            leftIcon={<RefreshCw className="w-5 h-5" />}
+            className="whitespace-nowrap"
+            title={t('email.incoming.pollHint', 'Check the mailbox now instead of waiting for the 60-second poll. Ingests unread attachments into Incoming invoices.') as string}
+          >
+            {t('email.incoming.poll', 'Check now')}
+          </Button>
           <Button variant="primary" onClick={() => save.mutate()} isLoading={save.isPending} leftIcon={<Save className="w-5 h-5" />} className="flex-1 min-w-[12rem]">
             {t('email.incoming.save', 'Save Incoming Mail Settings')}
           </Button>

frontend/src/i18n/locales/de.json

@@ -2486,6 +2486,13 @@
       "roundTripHint": "Sendet über die SMTP-Einstellungen eine Test-E-Mail an dieses Postfach und prüft, ob sie ankommt. Beide vorher speichern.",
       "roundTripOk": "Rundlauf OK — an {{recipient}} zugestellt in {{seconds}}s.",
       "roundTripFailed": "Rundlauf-Test fehlgeschlagen.",
+      "poll": "Jetzt prüfen",
+      "pollHint": "Postfach sofort prüfen, statt auf den 60-Sekunden-Abruf zu warten. Ungelesene Anhänge werden in Eingangsrechnungen übernommen.",
+      "pollOk": "Postfach geprüft — {{count}} neue E-Mail(s) übernommen.",
+      "pollDisabled": "Eingehende E-Mails sind deaktiviert — unter Einstellungen → Funktionen aktivieren.",
+      "pollUnconfigured": "Zuerst die Einstellungen für eingehende E-Mails speichern.",
+      "pollBusy": "Ein Abruf läuft bereits — bitte gleich erneut versuchen.",
+      "pollFailed": "Postfach-Abruf fehlgeschlagen.",
       "port": "Port",
       "security": "Sicherheit",
       "ssl": "SSL/TLS",

frontend/src/i18n/locales/en.json

@@ -2059,6 +2059,13 @@
       "roundTripHint": "Sends a test email via your SMTP settings to this mailbox and confirms it arrives. Save both first.",
       "roundTripOk": "Round-trip OK — delivered to {{recipient}} in {{seconds}}s.",
       "roundTripFailed": "Round-trip test failed.",
+      "poll": "Check now",
+      "pollHint": "Check the mailbox now instead of waiting for the 60-second poll. Ingests unread attachments into Incoming invoices.",
+      "pollOk": "Checked mailbox — {{count}} new email(s) ingested.",
+      "pollDisabled": "Incoming mail is turned off — enable it under Settings → Features.",
+      "pollUnconfigured": "Save the incoming mail settings first.",
+      "pollBusy": "A poll is already running — try again in a moment.",
+      "pollFailed": "Mailbox poll failed.",
       "port": "Port",
       "security": "Security",
       "ssl": "SSL/TLS",

frontend/src/services/email.service.ts

@@ -108,6 +108,11 @@ export interface ImapRoundTripResult {
   recipient?: string;
 }
 
+export interface ImapPollResult {
+  processed?: number;
+  skipped?: 'disabled' | 'unconfigured' | 'busy';
+}
+
 export interface ReceivedEmail {
   id: number;
   message_id: string | null;
@@ -162,6 +167,11 @@ export const emailService = {
     const response = await api.post<ImapRoundTripResult>('/admin/email/incoming-config/roundtrip', {});
     return response.data;
   },
+  // Run the poller on demand. Returns { processed } or { skipped: '…' }.
+  async pollIncoming(): Promise<ImapPollResult> {
+    const response = await api.post<ImapPollResult>('/admin/email/incoming-config/poll', {});
+    return response.data;
+  },
   async listReceived(params: { page?: number; pageSize?: number } = {}): Promise<ReceivedEmailsResponse> {
     const response = await api.get<ReceivedEmailsResponse>('/admin/email/received', { params });
     return response.data;