diff --git a/libs/growth/src/lib/webhooks.spec.ts b/libs/growth/src/lib/webhooks.spec.ts
index 0ffb7b461..c748c4db3 100644
--- a/libs/growth/src/lib/webhooks.spec.ts
+++ b/libs/growth/src/lib/webhooks.spec.ts
@@ -312,6 +312,41 @@ describe('processVerifiedResendWebhook', () => {
     }
   });
 
+  it('accepts the documented Resend payload shape: message_id present and null optional ids', async () => {
+    // Resend's wire payload gained `message_id` after SDK 6.10 pinned its
+    // types, and transactional mail carries null broadcast/template ids.
+    // Both must parse, or every real event answers 400 and delivery state
+    // never leaves "submitted".
+    const harness = webhookHarness();
+
+    await expect(
+      processVerifiedResendWebhook(
+        harness.executor,
+        {
+          providerEventId: 'msg_documented_shape',
+          payload: event('email.delivered', {
+            broadcast_id: null,
+            template_id: null,
+            message_id: '<111-222-333@email.example.com>',
+          }),
+        },
+        harness.dependencies
+      )
+    ).resolves.toMatchObject({ applied: true });
+  });
+
+  it('still rejects unknown data keys so the closed schema stays enforced', async () => {
+    const harness = executorWith({});
+
+    await expect(
+      processVerifiedResendWebhook(harness.executor, {
+        providerEventId: 'msg_unknown_key',
+        payload: event('email.delivered', { headers: [] }),
+      })
+    ).rejects.toThrow(/Invalid Resend webhook payload/u);
+    expect(harness.runTransaction).not.toHaveBeenCalled();
+  });
+
   it('marks only a permanent bounce as a hard-bounce stop', async () => {
     const hard = webhookHarness();
     await processVerifiedResendWebhook(
diff --git a/libs/growth/src/lib/webhooks.ts b/libs/growth/src/lib/webhooks.ts
index 6fd3eae27..3347ef6f7 100644
--- a/libs/growth/src/lib/webhooks.ts
+++ b/libs/growth/src/lib/webhooks.ts
@@ -32,11 +32,14 @@ const DELIVERY_STATUS_PRECEDENCE: Readonly<
   suppressed: 3,
   complained: 4,
 };
+// Resend's wire payload gained `message_id` after the pinned SDK types were
+// written, and transactional mail carries null broadcast/template ids.
 const BASE_DATA_KEYS = new Set([
   'broadcast_id',
   'created_at',
   'email_id',
   'from',
+  'message_id',
   'subject',
   'tags',
   'template_id',
@@ -184,9 +187,14 @@ function validateProviderBaseData(data: Record<string, unknown>): void {
     throw new Error('Invalid Resend webhook payload');
   }
   for (const recipient of data['to']) boundedText(recipient, 254);
-  if (data['broadcast_id'] !== undefined)
-    boundedText(data['broadcast_id'], 256);
-  if (data['template_id'] !== undefined) boundedText(data['template_id'], 256);
+  for (const key of ['broadcast_id', 'template_id'] as const) {
+    if (data[key] !== undefined && data[key] !== null) {
+      boundedText(data[key], 256);
+    }
+  }
+  if (data['message_id'] !== undefined && data['message_id'] !== null) {
+    boundedText(data['message_id'], 998);
+  }
 }
 
 function validateClosedDetails(