Very strange issue here. Around the time the 5s came out I went into AT&T to grab a new phone. For some reason I couldn't get logged into my apple account during setup so the AT&T employee completed the activation while using their account.
Ever since then when I did factory resets and after I entered my own apple credentials it would always ask me to log in with their account as well. Didn't bother me too much and I figured it was something particular to the phone.
However, I just bought a new 7 and the same issue has come up! After I log in with my account it asks me to log in with this strangers account. Obviously the accounts are linked in some fashion but I've checked every single account setting I can and I have no idea how this could have happened.
Anyone have any ideas?
Edit: It's not a used phone, but were new out of the box at AT&T. Also, doesn't sounds like it's an activation lock because it has followed me across phones. Definitely seems like an iTunes/Apple ID account issue.
Here's the popup that shows up right after a restore and when I open various apps following a restore. For what it's worth, this appears to be their personal email and not a corporate email:
Best Answer
This sounds like Activation Lock (Find My iPhone). That's a bummer, they shouldn't have signed in like that. If this is a new device I'd take it back and get another one, personally. Don't have them setup your phone afterwards.
If you don't want to return it, you'll need that Apple ID account name and password in order to complete setting it up and then signing out of iCloud to turn off Find My iPhone.