diff --git a/src/api/__tests__/list-properties.test.ts b/src/api/__tests__/list-properties.test.ts
new file mode 100644
index 00000000..626138e8
--- /dev/null
+++ b/src/api/__tests__/list-properties.test.ts
@@ -0,0 +1,16 @@
+import { describe, it, expect, vi } from 'vitest';
+
+vi.mock('../jmap-client', () => ({ jmapClient: { accountId: 'acc-1', request: vi.fn() } }));
+
+import { EMAIL_FULL_PROPERTIES, EMAIL_LIST_PROPERTIES, THREAD_HEADER_PROPERTIES } from '../email';
+
+// Sort by "Date sent" compares sentAt on the device for a list merged from
+// several accounts, but list rows never had it, so the order fell back to
+// the received date (webmail #1219).
+describe('list properties', () => {
+  it('include sentAt, once', () => {
+    for (const list of [EMAIL_LIST_PROPERTIES, EMAIL_FULL_PROPERTIES, THREAD_HEADER_PROPERTIES]) {
+      expect(list.filter((p) => p === 'sentAt')).toHaveLength(1);
+    }
+  });
+});
diff --git a/src/api/__tests__/live-stalwart-mail.test.ts b/src/api/__tests__/live-stalwart-mail.test.ts
index 88f46e8a..cce22afb 100644
--- a/src/api/__tests__/live-stalwart-mail.test.ts
+++ b/src/api/__tests__/live-stalwart-mail.test.ts
@@ -445,6 +445,8 @@ live('live Stalwart: mail, contacts, search (0.16 and 1.0)', () => {
       const row = page.list.find((e) => e.id === id);
       expect(row).toBeDefined();
       expect(senderWarningOf(row!)?.status).toBe('failed');
+      // The Date header, for sorting by date sent in merged lists (bulwarkmail/webmail#1219).
+      expect(typeof row!.sentAt).toBe('string');
       // The full fetch reads the same verdict from `headers`.
       const [full] = await getFullEmails([id]);
       expect(senderWarningOf(full)?.status).toBe('failed');
diff --git a/src/api/email.ts b/src/api/email.ts
index 7ad3b9d2..c1f975c9 100644
--- a/src/api/email.ts
+++ b/src/api/email.ts
@@ -24,6 +24,9 @@ import { LIST_AUTH_RESULTS_PROPERTY } from '../lib/email-headers';
 const EMAIL_SUMMARY_PROPERTIES = [
   'id', 'threadId', 'mailboxIds', 'keywords', 'size',
   'receivedAt', 'from', 'to', 'cc', 'subject', 'preview', 'hasAttachment',
+  // Sorting by "Date sent" compares it on the device for a list merged from
+  // several accounts; without it the order fell back to receivedAt (#1219).
+  'sentAt',
 ];
 
 export const EMAIL_LIST_PROPERTIES = [
@@ -41,7 +44,7 @@ export const EMAIL_LIST_PROPERTIES = [
 export const EMAIL_FULL_PROPERTIES = [
   ...EMAIL_SUMMARY_PROPERTIES,
   'bodyStructure', 'textBody', 'htmlBody', 'bodyValues',
-  'attachments', 'blobId', 'bcc', 'replyTo', 'sentAt',
+  'attachments', 'blobId', 'bcc', 'replyTo',
   'messageId', 'inReplyTo', 'references', 'headers',
 ];
 
@@ -1024,7 +1027,7 @@ export async function getEmailFlags(
 }
 
 // What a collapsed conversation card shows; `sentAt` is the date it prints.
-export const THREAD_HEADER_PROPERTIES = [...EMAIL_LIST_PROPERTIES, 'sentAt'];
+export const THREAD_HEADER_PROPERTIES = EMAIL_LIST_PROPERTIES;
 
 /** A conversation's members, oldest first, without bodies. */
 export interface ThreadHeaders {