diff --git a/lib/__tests__/unified-mailbox-cross.test.ts b/lib/__tests__/unified-mailbox-cross.test.ts
index 9c261a546..28589e426 100644
--- a/lib/__tests__/unified-mailbox-cross.test.ts
+++ b/lib/__tests__/unified-mailbox-cross.test.ts
@@ -45,6 +45,14 @@ describe('getCrossIncludedMailboxes', () => {
     expect(ids).toEqual(['inbox', 'projects']);
   });
 
+  it('excludes an RFC 6154 All mailbox, which would pull in sent/archive mail (#1241)', () => {
+    const account = makeAccount({
+      accountId: 'a',
+      mailboxes: [mb('inbox', 'inbox'), mb('all', 'all'), mb('sent', 'sent')],
+    });
+    expect(getCrossIncludedMailboxes(account).map((m) => m.id)).toEqual(['inbox']);
+  });
+
   it('honors an explicit crossIncludedMailboxIds selection (folder picker)', () => {
     const account = makeAccount({
       accountId: 'a',
@@ -109,6 +117,14 @@ describe('getCrossUnreadTotal', () => {
     expect(getCrossUnreadTotal([a, b])).toBe(10);
   });
 
+  it('does not count inbox unread twice through an all mailbox (#1241)', () => {
+    const a = makeAccount({
+      accountId: 'a',
+      mailboxes: [mb('inbox', 'inbox', 1), mb('all', 'all', 1), mb('sent', 'sent', 0)],
+    });
+    expect(getCrossUnreadTotal([a])).toBe(1);
+  });
+
   it('counts only the selected folders when crossIncludedMailboxIds is set; shared accounts stay unrestricted', () => {
     // personal account narrowed to inbox only (projects excluded by the picker)
     const personal = makeAccount({
diff --git a/lib/jmap/types.ts b/lib/jmap/types.ts
index befd90f9f..04b906186 100644
--- a/lib/jmap/types.ts
+++ b/lib/jmap/types.ts
@@ -1077,8 +1077,10 @@ export function isCrossViewId(id: string): boolean {
 
 /**
  * Mailbox roles excluded from the cross-account views. Everything else (inbox
- * and custom/no-role folders) is included.
+ * and custom/no-role folders) is included. `all` (RFC 6154 \All) holds every
+ * message, so including it would bring back sent/archive mail and count inbox
+ * unread twice.
  */
 export const CROSS_EXCLUDED_ROLES: ReadonlySet<string> = new Set([
-  'junk', 'sent', 'archive', 'trash', 'drafts',
+  'junk', 'sent', 'archive', 'trash', 'drafts', 'all',
 ]);
diff --git a/lib/unified-mailbox.ts b/lib/unified-mailbox.ts
index 8fac05d5c..4e8815db1 100644
--- a/lib/unified-mailbox.ts
+++ b/lib/unified-mailbox.ts
@@ -370,7 +370,7 @@ export function fetchUnifiedMailboxCounts(
 // ─── Cross-account views (unread / starred / all) ─────────────────────────────
 //
 // These merge messages across EVERY account (including shared) and across all
-// folders except the CROSS_EXCLUDED_ROLES (junk, sent, archive, trash, drafts),
+// folders except the CROSS_EXCLUDED_ROLES (junk, sent, archive, trash, drafts, all),
 // i.e. inbox + custom folders, into one date-sorted list. Unlike the per-role
 // unified fan-out above, the query spans many mailboxes per account, so the
 // filter is built from each account's included-mailbox ids.