diff --git a/lib/__tests__/jmap-draft-lifecycle.test.ts b/lib/__tests__/jmap-draft-lifecycle.test.ts
index a01fc2cae..f876368a0 100644
--- a/lib/__tests__/jmap-draft-lifecycle.test.ts
+++ b/lib/__tests__/jmap-draft-lifecycle.test.ts
@@ -29,7 +29,7 @@ interface CapturedRequest { methodCalls: JMAPMethodCall[] }
  * Email/set create come back as notCreated; `failSubmission` does the same
  * for EmailSubmission/set.
  */
-function mockFlow({ failCreate = false, failSubmission = false } = {}) {
+function mockFlow({ failCreate = false, failSubmission = false, methodError = false, missingSubmission = false, emptyErrors = false } = {}) {
   const captured: CapturedRequest[] = [];
   vi.spyOn(globalThis, 'fetch').mockImplementation(async (_url, init) => {
     const body = JSON.parse((init as { body: string }).body) as CapturedRequest;
@@ -56,11 +56,14 @@ function mockFlow({ failCreate = false, failSubmission = false } = {}) {
             result.created = { [key]: { id: 'email-new-1' } };
           }
         }
+        if (emptyErrors) result.notCreated = {};
         if (args.destroy) {
           result.destroyed = args.destroy;
         }
         methodResponses.push(['Email/set', result, callId]);
       } else if (method === 'EmailSubmission/set') {
+        if (missingSubmission) continue;
+        if (methodError) { methodResponses.push(['error', { type: 'serverFail', description: 'Google unavailable; draft retained' }, callId]); continue; }
         methodResponses.push(['EmailSubmission/set',
           failSubmission
             ? { notCreated: { '1': { type: 'forbiddenFrom', description: 'not allowed' } } }
@@ -230,3 +233,16 @@ describe('draft replace lifecycle (#849)', () => {
     ]);
   });
 });
+
+describe('compose failure recovery', () => {
+  beforeEach(() => { vi.restoreAllMocks(); vi.spyOn(console, 'error').mockImplementation(() => {}); });
+  it.each([{ methodError: true }, { missingSubmission: true }])('does not claim success or delete the old draft without confirmation: %j', async options => {
+    const client = createClient(); const captured = mockFlow(options);
+    await expect(client.sendEmail(['bob@example.com'], 'Subject', 'body', undefined, undefined, 'identity-1', 'user@example.com', 'old-draft')).rejects.toThrow();
+    expect(emailSetCalls(captured).some(call => call.destroy)).toBe(false);
+  });
+  it('accepts empty notCreated maps as success', async () => {
+    const client = createClient(); mockFlow({ emptyErrors: true });
+    expect(await client.createDraft(['bob@example.com'], 'Subject', 'body')).toBe('email-new-1');
+  });
+});
diff --git a/lib/jmap/client.ts b/lib/jmap/client.ts
index 1ce01fa06..f7a64de5c 100644
--- a/lib/jmap/client.ts
+++ b/lib/jmap/client.ts
@@ -3868,7 +3868,8 @@ export class JMAPClient implements IJMAPClient {
     if (response.methodResponses?.[0]?.[0] === "Email/set") {
       const result = response.methodResponses[0][1];
 
-      if (result.notCreated) {
+      // An empty notCreated map is a success some servers spell out.
+      if (result.notCreated && Object.keys(result.notCreated).length) {
         const errors = result.notCreated;
         const firstError = Object.values(errors)[0] as { description?: string; type?: string };
         console.error('Draft save error:', firstError);
@@ -4134,7 +4135,7 @@ export class JMAPClient implements IJMAPClient {
 
     if (response.methodResponses) {
       for (const [methodName, result] of response.methodResponses) {
-        if (result.notCreated) {
+        if (result.notCreated && Object.keys(result.notCreated).length) {
           // Include method name + full error object so it's clear whether the
           // failure came from Email/set (draft create) or EmailSubmission/set
           // (actual send) and which JMAP error type/properties were returned.
@@ -4188,6 +4189,13 @@ export class JMAPClient implements IJMAPClient {
       }
     }
 
+    // No EmailSubmission came back - a method error, or no answer for it at
+    // all. Nothing confirms the message left: report a failure and keep the
+    // old draft rather than replacing it as if the send had worked.
+    if (!emailSubmissionId) {
+      throw new Error('Send confirmation was not received. Check Sent before sending again. Your draft has been kept.');
+    }
+
     // With every recipient refused nothing was queued, yet the submission
     // exists and its onSuccessUpdateEmail filed the copy into Sent (#1123).
     // Drop that copy and keep the old draft: the send failed.