Immediate performance of actions attempted while offline and syncing of them once connection is restored would be a huge improvement to the app for those who are frequently offline (especially those who commute via subway, travel frequently, etc). Ideally, Mark as Unread, Archive, and similar actions would appear to the user to have been performed immediately (eliminating annoying situations where repeated swipes do nothing, etc), and they would be enacted / performed when the app reconnects to the server again.