We have seen a large increase of blocking of email servers done by AT&T since they took over BellSouth and SBCGlobal. When it came to BellSouth we've had a difficult time communicating with the postmasters and locating the blocklists that would generate delays, SMTP Protocol Connection Failed messages, and just regular rejects. Just recently an email message from the AT&T servers indicated a delisting page that we've been able to use with much success: http://worldnet.att.net/general-info/mail_info/block_admin.html . This page can be used by those having issues with all three providers.
/Karl J
