diff --git a/src/main/renderer-settings.ts b/src/main/renderer-settings.ts
index 4aa517a..ac219b5 100644
--- a/src/main/renderer-settings.ts
+++ b/src/main/renderer-settings.ts
@@ -30,7 +30,11 @@ function validateJsonValue(value: unknown, depth = 0): void {
   }
   const entries = Object.entries(value as Record<string, unknown>);
   if (entries.length > 10_000) invalid();
-  entries.forEach(([, entry]) => validateJsonValue(entry, depth + 1));
+  entries.forEach(([, entry]) => {
+    if (entry !== undefined) {
+      validateJsonValue(entry, depth + 1);
+    }
+  });
 }
 
 function validateTopLevelType(value: unknown, expected: unknown): void {
@@ -64,6 +68,9 @@ export function validateRendererSettingsUpdate(value: unknown, current: AppSetti
   const input = value as Record<string, unknown>;
   const output: Record<string, unknown> = {};
   for (const [key, entry] of Object.entries(input)) {
+    if (entry === undefined) {
+      continue;
+    }
     if (DERIVED_KEYS.has(key)) {
       continue;
     }
diff --git a/tests/renderer-settings.test.ts b/tests/renderer-settings.test.ts
new file mode 100644
index 0000000..64aeac8
--- /dev/null
+++ b/tests/renderer-settings.test.ts
@@ -0,0 +1,40 @@
+import { describe, expect, it } from "vitest";
+import { defaultSettings } from "../src/main/constants";
+import { createRendererSettings } from "../src/main/renderer-state";
+import { validateRendererSettingsUpdate } from "../src/main/renderer-settings";
+
+describe("renderer settings validation", () => {
+  it("accepts a complete settings save when an account status has no optional email", () => {
+    const current = defaultSettings();
+    current.debridAccountStatuses = {
+      "svc-realdebrid": {
+        accountId: "svc-realdebrid",
+        provider: "realdebrid",
+        label: "Real-Debrid",
+        maskedLogin: "user",
+        valid: true,
+        isPremium: true,
+        premiumUntilMs: null,
+        message: "Premium aktiv",
+        checkedAt: 1_700_000_000_000
+      }
+    };
+    const rendererSettings = createRendererSettings(current);
+
+    expect(rendererSettings.debridAccountStatuses["svc-realdebrid"]).toHaveProperty("email", undefined);
+    const validated = validateRendererSettingsUpdate(rendererSettings, current);
+
+    expect(validated.debridAccountStatuses).toEqual(rendererSettings.debridAccountStatuses);
+    expect(validated.animatePackageDisclosure).toBe(true);
+    expect(validated).not.toHaveProperty("configuredProviders");
+    expect(validated).not.toHaveProperty("archivePasswordListConfigured");
+    expect(validated).not.toHaveProperty("notifyUrlConfigured");
+  });
+
+  it("ignores omitted optional top-level values but still rejects unknown concrete settings", () => {
+    const current = defaultSettings();
+
+    expect(validateRendererSettingsUpdate({ columnOrderVersion: undefined }, current)).toEqual({});
+    expect(() => validateRendererSettingsUpdate({ obsoleteSetting: true }, current)).toThrow("Settings-Payload ist ungültig");
+  });
+});