Are you getting sbcglobal.net email login error?
Don't bother, follow given steps to fix sign in AT & T account.
• If you find that your sbc account login credentials wrong then correct it by recovery through your email and login with new credentials
• Check sbcglobal server status before login into yahoo account.
• Check your browser’s settings to get rid of AT &T yahoo sign in problem.
• Clear all cache, cookies, and history