Mail.web att.com
It looks like you're trying to access the AT&T email service!
The correct URL for AT&T email is actually webmail.att.net
, not mail.web att.com
. You can try accessing your email by going to webmail.att.net
and logging in with your AT&T email address and password.
If you're having trouble accessing your email, you can also try contacting AT&T's customer support for assistance.