I have the same problem on my new Note 3 running Android 4.3 XXUBMJ1. Factory reset and firmware reload doesn't help. I did few test myself and notice the incident doesn't happen until I have my Exchange Account setup. Once I remove my Exchange Account, problem cease. Problem repeated for 2 times if I repeat the same test. So I highly suspect some bug in the Android Stock Email App (after I updated to XXUBMJ1) or the Exchange Policy impose by my Company IT or conflict between XXUBMJ1 and Security Policy. I don't have this problem before I updated to XXUBMJ1. Still no solution yet and very annoying. Strongly consider to remove my Exchange Account at the moment until new firmware release.