Hello, Could you please provide more info about your problem. What exactly doesn't work?. What did you tried to solve it?. Any screenshot if applicable.

Have a great day!

The main reason most users can't access AT&T accounts is not using a secure mail key in TB instead of the account password.

https://www.att.com/support/article/dsl-high-speed/KM1010523/

Thank you for the replies. I contacted AT&T customer clueless service to get a secure mail key and they informed me that AT&T doesn't support Thunderbird (or Gmail app on my phone) so I need to contact Mozilla. I tried multiple times to tell him that all I need is a new key but the idiot kept telling me the same thing!! Finally I tried searching myself and found on their site the create a new security key link and resolved it. It amazes me how these people get these jobs!!

Perhaps if you missed the link in the page sfhowes provided which took you to creating a secure mailkey.