Rolling back to 8.1 took away the default email inbox..

[heli0m]

I think it's because I restored with the Windows 10 backup where the new Outlook mail app is not available for Windows Phone 8.1. That's the only thing missing. Of course, there are alternative inboxes, but I wonder if a hard reset to the same backup will bring back the default app. (I don't know, just a question.)

 

[snak251]

a hard reset may solve your problem