diff --git a/src/lib-storage/mail-storage.c b/src/lib-storage/mail-storage.c
index 43d52b5985..02beaa6e45 100644
--- a/src/lib-storage/mail-storage.c
+++ b/src/lib-storage/mail-storage.c
@@ -880,6 +880,8 @@ bool mailbox_is_autocreated(struct mailbox *box)
 {
 	if (box->inbox_user)
 		return TRUE;
+	if ((box->flags & MAILBOX_FLAG_AUTO_CREATE) != 0)
+		return TRUE;
 	return box->set != NULL &&
 		strcmp(box->set->autocreate, MAILBOX_SET_AUTO_NO) != 0;
 }
diff --git a/src/lib-storage/mail-storage.h b/src/lib-storage/mail-storage.h
index 85ad9e6f22..830dbe5f19 100644
--- a/src/lib-storage/mail-storage.h
+++ b/src/lib-storage/mail-storage.h
@@ -61,6 +61,8 @@ enum mailbox_flags {
 	   The backend shouldn't treat it as corruption if a mail body isn't
 	   found. */
 	MAILBOX_FLAG_USE_STUBS		= 0x800,
+	/* Mailbox is created implicitly if it does not exist. */
+	MAILBOX_FLAG_AUTO_CREATE	= 0x1000,
 };
 
 enum mailbox_feature {