diff --git a/src/main/app-controller.ts b/src/main/app-controller.ts
index 3481ec9..46eda7f 100644
--- a/src/main/app-controller.ts
+++ b/src/main/app-controller.ts
@@ -1287,7 +1287,7 @@ export class AppController {
     return this.manager.getItemLogPath(itemId) || getItemLogPath(itemId);
   }
 
-  public shutdown(): void {
+  public async shutdown(): Promise<void> {
     if (this.runtimeStatsTimer) {
       clearInterval(this.runtimeStatsTimer);
       this.runtimeStatsTimer = null;
@@ -1295,7 +1295,7 @@ export class AppController {
     stopDebugServer();
     abortActiveUpdateDownload();
     cancelPendingAsyncSaves();
-    void this.notificationOutbox.drainForShutdown().catch((error) => {
+    await this.notificationOutbox.drainForShutdown(3000).catch((error) => {
       logger.warn(`Notification-Outbox konnte beim Beenden nicht geleert werden: ${String(error)}`);
     });
     this.manager.prepareForShutdown();
diff --git a/src/main/main.ts b/src/main/main.ts
index 44151a3..433a38e 100644
--- a/src/main/main.ts
+++ b/src/main/main.ts
@@ -92,7 +92,42 @@ let scheduledStartTimer: ReturnType<typeof setTimeout> | null = null;
 let lastClipboardText = "";
 let controller: AppController;
 let pendingBackupImport: Buffer | null = null;
-const CLIPBOARD_MAX_TEXT_CHARS = 50_000;
+const CLIPBOARD_MAX_TEXT_CHARS = 50_000;
+
+export interface BeforeQuitHandlerOptions {
+  cleanup: () => void;
+  shutdown: () => Promise<void>;
+  continueQuit: () => void;
+  onError: (error: unknown) => void;
+}
+
+export function createBeforeQuitHandler(options: BeforeQuitHandlerOptions): (event: { preventDefault: () => void }) => void {
+  let shutdownStarted = false;
+  let quitAllowed = false;
+  return (event) => {
+    if (quitAllowed) {
+      return;
+    }
+    event.preventDefault();
+    if (shutdownStarted) {
+      return;
+    }
+    shutdownStarted = true;
+    let shutdown: Promise<void>;
+    try {
+      options.cleanup();
+      shutdown = options.shutdown();
+    } catch (error) {
+      shutdown = Promise.reject(error);
+    }
+    void shutdown.catch((error) => {
+      options.onError(error);
+    }).finally(() => {
+      quitAllowed = true;
+      options.continueQuit();
+    });
+  };
+}
 
 function isDevMode(): boolean {
   return process.env.NODE_ENV === "development";
@@ -1038,16 +1073,20 @@ app.on("window-all-closed", () => {
   }
 });
 
-app.on("before-quit", () => {
-  if (updateQuitTimer) { clearTimeout(updateQuitTimer); updateQuitTimer = null; }
-  stopClipboardWatcher();
-  destroyTray();
-  shutdownDaemon();
-  if (controller) {
-    try {
-      controller.shutdown();
-    } catch (error) {
-      logger.error(`Fehler beim Shutdown: ${String(error)}`);
+app.on("before-quit", createBeforeQuitHandler({
+  cleanup: () => {
+    if (updateQuitTimer) { clearTimeout(updateQuitTimer); updateQuitTimer = null; }
+    stopClipboardWatcher();
+    destroyTray();
+    shutdownDaemon();
+  },
+  shutdown: async () => {
+    if (controller) {
+      await controller.shutdown();
     }
+  },
+  continueQuit: () => app.quit(),
+  onError: (error) => {
+    logger.error(`Fehler beim Shutdown: ${String(error)}`);
   }
-});
+}));
diff --git a/src/main/notification-outbox.ts b/src/main/notification-outbox.ts
index 9067da6..aaff963 100644
--- a/src/main/notification-outbox.ts
+++ b/src/main/notification-outbox.ts
@@ -132,7 +132,7 @@ function oldestIndex(events: NotificationEvent[], predicate: (event: Notificatio
 }
 
 function retryDelayMs(attempts: number): number {
-  return Math.min(MAX_RETRY_DELAY_MS, 1000 * (2 ** Math.min(9, Math.max(0, attempts - 1))));
+  return Math.min(MAX_RETRY_DELAY_MS, 1000 * (2 ** Math.min(30, Math.max(0, attempts - 1))));
 }
 
 export class NotificationOutbox {
@@ -153,6 +153,9 @@ export class NotificationOutbox {
     this.clock = options.now || Date.now;
     this.autoDrain = Boolean(options.autoDrain);
     this.load();
+    if (this.autoDrain && this.events.length > 0) {
+      this.scheduleDrain(Math.max(0, this.events[0].nextAttemptAt - this.clock()));
+    }
   }
 
   public async enqueue(event: NotificationEvent): Promise<void> {
@@ -170,11 +173,15 @@ export class NotificationOutbox {
 
   public drain(now?: number): Promise<void> {
     return this.runExclusive(async () => {
-      const drainAt = finiteInteger(now ?? this.clock());
-      this.enforceLimits(drainAt);
+      let currentNow = finiteInteger(now ?? this.clock());
+      this.enforceLimits(currentNow);
       while (this.events.length > 0) {
         const current = this.events[0];
-        if (current.nextAttemptAt > drainAt) {
+        if (current.nextAttemptAt > currentNow) {
+          await this.persist(currentNow);
+          if (this.autoDrain) {
+            this.scheduleDrain(Math.max(0, current.nextAttemptAt - this.clock()));
+          }
           break;
         }
         let sent = false;
@@ -183,23 +190,25 @@ export class NotificationOutbox {
         } catch {
           sent = false;
         }
+        const outcomeAt = finiteInteger(this.clock(), currentNow);
         if (!sent) {
           current.attempts += 1;
-          current.nextAttemptAt = drainAt + retryDelayMs(current.attempts);
-          this.lastFailureAt = drainAt;
-          await this.persist(drainAt);
+          current.nextAttemptAt = outcomeAt + retryDelayMs(current.attempts);
+          this.lastFailureAt = outcomeAt;
+          await this.persist(outcomeAt);
           if (this.autoDrain) {
             this.scheduleDrain(Math.max(0, current.nextAttemptAt - this.clock()));
           }
           break;
         }
         this.events.shift();
-        this.lastSuccessAt = drainAt;
-        await this.persist(drainAt);
+        this.lastSuccessAt = outcomeAt;
+        await this.persist(outcomeAt);
+        currentNow = finiteInteger(this.clock(), outcomeAt);
       }
       if (this.events.length === 0) {
         this.clearRetryTimer();
-        await this.persist(drainAt);
+        await this.persist(finiteInteger(this.clock(), currentNow));
       }
     });
   }
diff --git a/tests/main-shutdown-lifecycle.test.ts b/tests/main-shutdown-lifecycle.test.ts
new file mode 100644
index 0000000..51fa439
--- /dev/null
+++ b/tests/main-shutdown-lifecycle.test.ts
@@ -0,0 +1,100 @@
+import { describe, expect, it, vi } from "vitest";
+
+const electron = vi.hoisted(() => {
+  const handlers = new Map<string, (...args: unknown[]) => void>();
+  return {
+    handlers,
+    app: {
+      isPackaged: false,
+      getPath: vi.fn(() => "C:\\MDD\\Test"),
+      getAppPath: vi.fn(() => "C:\\MDD\\App"),
+      requestSingleInstanceLock: vi.fn(() => true),
+      on: vi.fn((name: string, handler: (...args: unknown[]) => void) => { handlers.set(name, handler); }),
+      whenReady: vi.fn(() => new Promise<void>(() => {})),
+      quit: vi.fn(),
+      exit: vi.fn(),
+      setPath: vi.fn()
+    }
+  };
+});
+
+vi.mock("electron", () => ({
+  app: electron.app,
+  BrowserWindow: class {
+    public static getAllWindows(): unknown[] { return []; }
+  },
+  clipboard: {},
+  dialog: {},
+  ipcMain: { handle: vi.fn(), on: vi.fn() },
+  Menu: { buildFromTemplate: vi.fn(), setApplicationMenu: vi.fn() },
+  safeStorage: { isEncryptionAvailable: () => false, encryptString: vi.fn(), decryptString: vi.fn() },
+  shell: { openExternal: vi.fn() },
+  Tray: class {}
+}));
+
+import { AppController } from "../src/main/app-controller";
+
+function deferred(): { promise: Promise<void>; resolve: () => void } {
+  let resolve = () => {};
+  const promise = new Promise<void>((done) => { resolve = done; });
+  return { promise, resolve };
+}
+
+describe("main shutdown lifecycle", () => {
+  it("AppController waits for the bounded outbox drain before disposing runtime owners", async () => {
+    const drain = deferred();
+    const manager = { prepareForShutdown: vi.fn() };
+    const controller = Object.create(AppController.prototype) as any;
+    controller.runtimeStatsTimer = null;
+    controller.notificationOutbox = { drainForShutdown: vi.fn(() => drain.promise) };
+    controller.manager = manager;
+    controller.megaWebFallback = { dispose: vi.fn() };
+    controller.realDebridWebFallbacks = new Map();
+    controller.pendingRealDebridWebAccountIds = new Map();
+    controller.allDebridWebFallback = { dispose: vi.fn() };
+    controller.bestDebridWebFallback = { dispose: vi.fn() };
+    controller.shutdownLogStorage = vi.fn();
+    controller.audit = vi.fn();
+    controller.settings = { historyRetentionMode: "never" };
+
+    const shutdown = controller.shutdown();
+
+    expect(shutdown).toBeInstanceOf(Promise);
+    expect(controller.notificationOutbox.drainForShutdown).toHaveBeenCalledWith(3000);
+    expect(manager.prepareForShutdown).not.toHaveBeenCalled();
+    drain.resolve();
+    await shutdown;
+    expect(manager.prepareForShutdown).toHaveBeenCalledTimes(1);
+  });
+
+  it("prevents quit once, waits for shutdown, then allows exactly one loop-free quit", async () => {
+    const main = await import("../src/main/main");
+    const shutdown = deferred();
+    const cleanup = vi.fn();
+    const continueQuit = vi.fn();
+    const onError = vi.fn();
+    const handler = main.createBeforeQuitHandler({
+      cleanup,
+      shutdown: vi.fn(() => shutdown.promise),
+      continueQuit,
+      onError
+    });
+    const first = { preventDefault: vi.fn() };
+    const repeated = { preventDefault: vi.fn() };
+    const resumed = { preventDefault: vi.fn() };
+
+    handler(first);
+    handler(repeated);
+    expect(first.preventDefault).toHaveBeenCalledTimes(1);
+    expect(repeated.preventDefault).toHaveBeenCalledTimes(1);
+    expect(cleanup).toHaveBeenCalledTimes(1);
+    expect(continueQuit).not.toHaveBeenCalled();
+
+    shutdown.resolve();
+    await vi.waitFor(() => expect(continueQuit).toHaveBeenCalledTimes(1));
+    handler(resumed);
+    expect(resumed.preventDefault).not.toHaveBeenCalled();
+    expect(cleanup).toHaveBeenCalledTimes(1);
+    expect(onError).not.toHaveBeenCalled();
+  });
+});
diff --git a/tests/notification-outbox.test.ts b/tests/notification-outbox.test.ts
index b358099..74716e7 100644
--- a/tests/notification-outbox.test.ts
+++ b/tests/notification-outbox.test.ts
@@ -4,6 +4,7 @@ import os from "node:os";
 import path from "node:path";
 import { afterEach, describe, expect, it, vi } from "vitest";
 import { NotificationEvent, NotificationOutbox } from "../src/main/notification-outbox";
+import { sendNotification } from "../src/main/notify";
 
 const tempDirs: string[] = [];
 
@@ -67,11 +68,12 @@ describe("NotificationOutbox", () => {
 
   it("backs off a failed event without allowing later events to overtake it", async () => {
     const filePath = createOutboxFile();
+    let now = 1000;
     const outcomes = [false, true, true];
     const sent: string[] = [];
     const outbox = new NotificationOutbox({
       filePath,
-      now: () => 1000,
+      now: () => now,
       send: async (queuedEvent) => {
         sent.push(queuedEvent.id);
         return outcomes.shift() ?? true;
@@ -80,17 +82,115 @@ describe("NotificationOutbox", () => {
 
     await outbox.enqueue(event("first"));
     await outbox.enqueue(event("second"));
-    await outbox.drain(1000);
+    await outbox.drain();
     expect(sent).toEqual(["first"]);
     expect(persisted(filePath).events[0]).toMatchObject({ id: "first", attempts: 1, nextAttemptAt: 2000 });
     expect(outbox.getStatus()).toEqual({ queued: 2, lastSuccessAt: 0, lastFailureAt: 1000 });
 
-    await outbox.drain(1999);
+    now = 1999;
+    await outbox.drain();
     expect(sent).toEqual(["first"]);
-    await outbox.drain(2000);
+    now = 2000;
+    await outbox.drain();
     expect(sent).toEqual(["first", "first", "second"]);
   });
 
+  it("uses the actual failure time for retry backoff", async () => {
+    const filePath = createOutboxFile();
+    let now = 1000;
+    const outbox = new NotificationOutbox({
+      filePath,
+      now: () => now,
+      send: async () => {
+        now = 4500;
+        return false;
+      }
+    });
+
+    await outbox.enqueue(event("late-failure"));
+    await outbox.drain();
+
+    expect(persisted(filePath).events[0]).toMatchObject({ attempts: 1, nextAttemptAt: 5500 });
+    expect(outbox.getStatus().lastFailureAt).toBe(4500);
+  });
+
+  it("rechecks expiration after each send before delivering the next event", async () => {
+    const filePath = createOutboxFile();
+    let now = 1000;
+    const sent: string[] = [];
+    const outbox = new NotificationOutbox({
+      filePath,
+      now: () => now,
+      send: async (queuedEvent) => {
+        sent.push(queuedEvent.id);
+        now = 2000;
+        return true;
+      }
+    });
+
+    await outbox.enqueue(event("first", { expiresAt: 5000 }));
+    await outbox.enqueue(event("expires-during-send", { expiresAt: 1500 }));
+    await outbox.drain();
+
+    expect(sent).toEqual(["first"]);
+    expect(outbox.getStatus()).toEqual({ queued: 0, lastSuccessAt: 2000, lastFailureAt: 0 });
+  });
+
+  it("caps exponential retry backoff at ten minutes after many attempts", async () => {
+    const filePath = createOutboxFile();
+    let now = 1000;
+    const outbox = new NotificationOutbox({
+      filePath,
+      now: () => now,
+      send: async () => {
+        now = 2000;
+        return false;
+      }
+    });
+
+    await outbox.enqueue(event("many-attempts", { attempts: 20 }));
+    await outbox.drain();
+
+    expect(persisted(filePath).events[0]).toMatchObject({ attempts: 21, nextAttemptAt: 602000 });
+  });
+
+  it("restores a future retry timer and reads changed URL and mention only when retrying", async () => {
+    vi.useFakeTimers();
+    vi.setSystemTime(1000);
+    const filePath = createOutboxFile();
+    const firstUrl = "https://discord.example.test/api/webhooks/first";
+    const secondUrl = "https://discord.example.test/api/webhooks/second";
+    let settings = { url: firstUrl, mention: "111111" };
+    const fetchFn = vi.fn()
+      .mockResolvedValueOnce(new Response("", { status: 404 }))
+      .mockResolvedValueOnce(new Response(null, { status: 204 }));
+    const sender = (queuedEvent: NotificationEvent): Promise<boolean> => sendNotification(settings.url, {
+      title: queuedEvent.payload.title,
+      message: queuedEvent.payload.description || "",
+      mention: settings.mention,
+      fields: queuedEvent.payload.fields,
+      timestamp: queuedEvent.createdAt
+    }, fetchFn, async () => {});
+    const firstProcess = new NotificationOutbox({ filePath, send: sender });
+
+    await firstProcess.enqueue(event("restart-retry"));
+    await firstProcess.drain();
+    expect(persisted(filePath).events[0]).toMatchObject({ attempts: 1, nextAttemptAt: 2000 });
+
+    settings = { url: secondUrl, mention: "222222" };
+    const restartedProcess = new NotificationOutbox({ filePath, send: sender, autoDrain: true });
+    await vi.advanceTimersByTimeAsync(999);
+    expect(fetchFn).toHaveBeenCalledTimes(1);
+    await vi.advanceTimersByTimeAsync(1);
+    expect(fetchFn).toHaveBeenCalledTimes(2);
+    expect(fetchFn.mock.calls[0][0]).toBe(firstUrl);
+    expect(fetchFn.mock.calls[1][0]).toBe(secondUrl);
+    expect(JSON.parse(String(fetchFn.mock.calls[0][1]?.body)).content).toBe("<@111111>");
+    expect(JSON.parse(String(fetchFn.mock.calls[1][1]?.body)).content).toBe("<@222222>");
+    await restartedProcess.drain();
+    expect(persisted(filePath).events).toEqual([]);
+  });
+
   it("automatically drains new events and retries them at the persisted deadline", async () => {
     vi.useFakeTimers();
     vi.setSystemTime(1000);