The relationship between these three companies can be slightly confusing as long as you don’t have an understanding. So let us help you make things simpler.
www SBCGlobal net has, since 2005, becoming only SBC (Southwestern Bell Company). It was during this year that SBC acquired AT&T and decided to stick with the AT&T brand name since they were better known; thus, SBC became AT&T.
But before all this happened, there were people already using the legacy
SBCGlobal email settings service. So SBC put all their legacy customers on the AT&T Yahoo! Service. All this happened before AT&T cut off ties with Google, sometime in January of 2008, which resulted in a mass migration of all its webmail clients over to the Yahoo platform. So this is why SBCGlobal account holders now have to log in to their accounts through Yahoo’s att.net
SBCglobal Net Email Settings