I'm going to assume that SCBGlobal is a company that ATT bought, like they bought bellsouth here where I live. If that assumption is wrong, then everything I'm about to tell you is wrong too.
Through your regular mail app (not Gmail) you can add an account to go get your scbglobal mail. In the mail app, select menu, more, new account.
Your incoming (POP) server is probably going o be mail.scbglobal.com (or .net, if that's how your email account ends) security type = none, port 110. (your security and port could be different, those are what I use for my Bellsouth settings).
Your outgoing (SMTP) server will probably be smtp.att.yahoo.com, security type = SSL, port 465.
Of course it's going to be asking your for your user name and password along the way. You'll know right away if a server setting is wrong because it checks before moving on to the next step.
This MAY work under Gmail too, but I didn't believe that it would so I didn't try it, I went straight to the Mail app to get to my ATT email.