AT&T, Bellsouth and SBC overview

AT&T is one of the largest telecommunication providers in the United States.  The modern AT&T company was created in 1983 as the result of the breakup of the original AT&T telephone monopoly. The breakup of AT&T created numerous regional telephone providers including Bellsouth and Southwestern Bell (SBC). 

SBC acquired AT&T in 2005, assuming the AT&T company name, and subsequently acquired Bellsouth in 2006. 


AT&T, Bellsouth, and SBC use the Yahoo! email infrastructure to filter messages. The receiving Mail Transfer Agent (MTA) is located within AT&T's network. Messages accepted at the gateway by AT&T servers are relayed to the Yahoo! anti-spam filters, and displayed within the AT&T Yahoo! webmail platform. 


North America; U.S. 



Suggested MTA settings:

  • 5 simultaneous connections per sending IP address
    • 100 recipients per connection

Feedback loop (FBL) application 

Feedback Loop through Yahoo

Postmaster site

AT&T Postmaster; Yahoo! Postmaster


Return Path partnership with AT&T, Bellsouth and SBC 

AT&T, Bellsouth and SBC use Return Path’s Certified Whitelist through shared use of the Yahoo! Infrastructure.  Whitelisting includes, bellsouth and 

AT&T, Bellsouth and SBC delivery mediation 

AT&T has a public escalation process, which allows senders to email an unblock request to the block list group. AT&T also has information about the error codes they return available on their Postmaster website. 

Return Path guidance 

Return Path understands the Yahoo! infrastructure well and may have data to diagnose deliverability issues. Refer to both AT&T and Yahoo!’s deliverability best practices and postmaster page for additional details on improving deliverability.


Was this article helpful?
0 out of 0 found this helpful
Have more questions? Submit a request