Permanently Deleted E-mail Stuck
I have an old e-mail that keeps showing up in my Inbox in OWA in iOS 8.2. I've deleted and permanently deleted it in OWA. I can close the app and relaunch and it disappears for a while, but then comes back. I don't see it when I access the same corp Office365 e-mail on a PC through the web or Outlook. So it seems MS has something separate setup to support the OWA mobile app, which is causing the issue. Probably some temp files / cache that needs to be cleaned up for this on your servers. I doubt it's anything on my phone, as it does go away from there, but then it syncs it back from your OWA supporting servers.