diff --git a/backend/imap-idle/index.mjs b/backend/imap-idle/index.mjs
index 42e5281..5860d67 100644
--- a/backend/imap-idle/index.mjs
+++ b/backend/imap-idle/index.mjs
@@ -35,7 +35,14 @@ const ADMIN_SECRET =
   process.env.NUXT_ADMIN_SECRET || process.env.ADMIN_SECRET || "";
 
 const DB_REFRESH_INTERVAL_MS = 5 * 60 * 1000;   // 5 min — neue Connections entdecken
-const IDLE_RENEW_INTERVAL_MS = 25 * 60 * 1000;  // 25 min — RFC 3501 max = 29min
+// IDLE_RENEW von 25min → 10min: GMX dropped IDLE-connections silent vor 25min
+// → exists-events kommen nie an + ImapFlow.idle() hängt ohne reject. 10min
+// deckt alle bekannten Provider-Timeouts ab (GMX ~10-15min, Gmail ~29min,
+// iCloud ~29min, Outlook ~29min). Trade-off: alle 10min full reconnect-cycle.
+const IDLE_RENEW_INTERVAL_MS = 10 * 60 * 1000;  // 10 min (war 25)
+// NOOP-heartbeat alle 2min während IDLE: defensive check ob connection wirklich
+// alive ist. Wenn NOOP fehlschlägt → close + reconnect-loop.
+const IDLE_NOOP_INTERVAL_MS  = 2 * 60 * 1000;   // 2 min — silent-drop early-detection
 const RECONNECT_DELAYS_MS    = [1000, 5000, 30_000]; // exponential backoff, danach 60s loop
 const RECONNECT_LOOP_DELAY_MS = 60 * 1000;
 
@@ -205,15 +212,29 @@ async function runSession(conn) {
         };
         imap.on("exists", onExists);
 
-        // IDLE nach 25min erneuern (RFC 3501: Server darf nach 29min droppen)
+        // IDLE nach 10min erneuern (war 25; GMX dropped silent vor 25min)
         const renewTimer = setTimeout(() => {
-          log(conn.email, "idle renewing (25min threshold)");
+          log(conn.email, "idle renewing (10min threshold)");
           imap.close(); // Unterbricht idle() → Loop iteriert → reconnect
         }, IDLE_RENEW_INTERVAL_MS);
 
+        // NOOP-heartbeat alle 2min: detect silent-IDLE-drops (GMX-pattern).
+        // Wenn NOOP fehlschlägt → close → loop iteriert → reconnect.
+        const noopTimer = setInterval(async () => {
+          try {
+            await imap.noop();
+            // Optional: verbose-log für debugging — aktuell silent
+            // log(conn.email, "noop ok");
+          } catch (err) {
+            logError(conn.email, "noop failed — connection dead, force reconnect", err);
+            imap.close();
+          }
+        }, IDLE_NOOP_INTERVAL_MS);
+
         try {
           await idlePromise;
         } finally {
+          clearInterval(noopTimer);
           clearTimeout(renewTimer);
           imap.removeListener("exists", onExists);
         }