According to:
http://www.wireless.att.com/homemanager/faqs.jsp
Q. How do I set up my email account when the default configurations do not
work?
If the domain name at the end of your email address is one of the following:
ameritech.net, att.net, flash.net, nvbell.net, pacbell.net, prodigy.net,
sbcglobal.net, snet.net, swbell.net, or wans.net, then the default email
settings on the frame will be:
User Name: entire email address (for example: (e-mail address removed))
POP3 Server: pop.att.yahoo.com
POP3 Port: 995
POP3 Secure? SSL
SMTP Server: smtp.att.yahoo.com
SMTP Port: 465
SMTP Secure? SSL
SMTP Login? Checked
If those default email settings don't work, replace the default settings by
manually entering each of the following email settings into the frame:
User Name: Entire Email Address (for example: (e-mail address removed))
POP3 Server: fpostoffice.isp.att.net
POP3 Port: 995
POP3 Secure? SSL
SMTP Server: fmailhost.isp.att.net
SMTP Port: 465
SMTP Secure? SSL
SMTP Login? Checked