Mail Navigation On iPad
If you delete or archive a message on iPad in landscape orientation, Mail usually moves your selection up in the list, gradually working towards the ‘top’ of that inbox or folder. But if you’ve already read the next message ‘up’ in the list, and the next message below is unread, Mail will instead select the message below.
These heuristic subtleties aren’t exposed in app UI or advertised as features, but they fundamentally change the emotion you feel towards an app. This is what makes people come back and use your app again and again. Apple’s apps are great for these touches. iWork for iOS has loads of them.