Hmmm are you using the gmail application? If so, you could just add the account to your device using the AT&T BIS web page or by clicking the "personal email set up" icon.
Has anyone resolved this issue? I know that you can just add your email address to your message box, but I would like to have this program so other people can check as well if they want. I have been getting this error for a long time now and I have not been able to reconnect to gmail since it started happening.