[rambo47]

Those accounts are already disabled for BB10 users. I miss mine as it was a secure account that could only be accessed from my BlackBerry itself. Of course there are pitfalls, like no spam filtering and loss of access should you change carriers.

First, try a battery pull for a minute or so. Next step would be to double-check your settings against the recommended settings from AT&T. Finally, you can try deleting the account and re-adding it.