blocked by sbc:blacklist.mailrelay.att.net. 521 DNSRBL: Blocked for abuse.

Hi, since four months ago our e-mails have been blocked by AT&T with the following statement: att.net #521-187.216.86.  blocked by sbc:blacklist.mailrelay.att.net. 521 DNSRBL: Blocked for abuse.

Since users first reported this issue I sent the required information trough the required forms at http://att.net/blocks and do so in several repteated occasion and AT&T has failed to provide a single response for any one of those requests. It is seriously annoying as we are not in any other black list, and or DNS complies with AT&T requirements.

We need to get this solved as soon as possible because it's been months of this, having to use personal e-mails to conduct business with people that use AT&T's services.