SBCGLOBAL EMAIL SETTINGS

Change the incoming server settings to imap.mail.att.net in the Server field, 993 in the Port field, SSL/TLS in the Security field, complete username in the username field, and correct password in the Password field. Next, change the SBCGlobal email settings for Outgoing server to smtp.mail.att.net in the server field, 465 in the Port field, SSL/TLS in the security field, correct username and password in the username and password field respectively.

For more details: SBC Customer service