When I upgraded from iOS4 to iOS5 an unknown email address showed up as a possible email for me to set as one of my email accounts. Did anyone else have this problem? If so, where did it come from?
Is it possible that someone had access to your phone and/or your Apple ID? If someone tries to sign into iMessage using another email address (even without having your password) it will show up as an unverified alternate email in your Apple ID.
If they also added that email to your iPhone's
Mail.app they could reply to the verification email while on your device. All they would need then is to get your Apple ID password and they would have a validated account on your Apple ID. Then you would have an "extra" email account linked to your ID, even if they deleted the accounts off of the iPhone when they were done.
Best thing to do is to check your account at http://appleid.apple.com, verify that there are no more unknown email addresses, then change your password! Seriously! I saw this happen a lot when the upgrade from iOS 4 to iOS 5 first came out.
I agree, the email had to have been associated with that Apple ID before the iOS upgrade, whether ladybird56 knew about it or not. I just tested Neigborhood_nerd's theory that a failed iMessage login does add an unverified email to your Apple ID and then either has a password prompt popup or it autosends a verification email to that address. If they knew her password it would be the work of just a few seconds to respond to the verification email.
The only reason I can see that it showed up after the upgrade was that iOS 5 was the update that was the major overhaul that allowed for all wireless updating. Some research shows that many people had what looked like a "factory reset" condition after that upgrade was done, i.e. http://forums.macrumors.com/showthread.php?t=1255766
If that email address was associated with that apple id before the upgrade/reset, it will show up as an option to add as an email account during the setup process. Just like it would if she had gotten a new device.
No, nobody else has reported this problem according to my search.
All OS upgrades are tested and this kind of major bug would have been detected, so it is certain that the OS upgrade would have not added a new email account.
The email would have been there before, you just didn't notice it until now.