Sbcglobal e-mail adding to iPhone

I have an email address @sbcglobal.net. It was added to my iphone for years and it recently started saying it couldn't get e-mail and when going into settings it wanted me to re-enter my password. I couldn't get it to work so I deleted the account. When I go to re-enter it I can not get it to add. I have tried adding as yahoo, but it keeps wanting me to sign in with my @att.net ID then it adds the @att.net email not my @sbcglobal.net one. Then if I go to add it in mail as "other" it's saying my password/username is wrong and I know it's not as my @sbcglobal password should be the same at att.net password.

WHAT THE HECK IS GOING ON? I'm so frustrated with yahoo that I might just stop using the account I've had for over 14years!