Error in your SBCGlobal Email server.
Your Internet connection is slow or not working.
SBCGlobal email login related issues due to entering incorrect account credentials.
Someone logged into your SBCGlobal email account without your permission.
Your SBCGlobal email account has been blocked, according to Yahoo, for security reasons.
SBCGlobal Server settings related configuration are incorrect.
Above are the best steps to fix SBCGlobal Email Login Issues.