Not able to login your ATT email account.
ATT not working in Outlook.
Not able to send or receive emails.
Website of ATT is not working properly.
ATT not working in Android or iPhone.
Password of ATT email account is not working.
Above mentioned are the best Troubleshoot method for ATT Email Issues.
See Also this post:- https://www.datarecovo.com/att-email-settings-for-outlook/