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Basically I'm having an issue where I'm sending an e-mail from our exchange environment to @sbcglobal.net or @comcast.net and instantly getting kicked back.

nlpi134.prodigy.net #553 5.3.0 nlpi134 DNSBL:ATTRBL 521< 208.76.173.8 >_is_blocked.__For_information_see_http://att.net/blocks ##

In the header it has the internal mail server address mail.domain.local which I'm assuming is the issue here but EVERYwhere I've looked i have the proper DNS names, PTR's and SPF records in place and I just continue getting the same reponse

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2 Answers 2

Have you followed the steps detailed at http://www.att.net/general-info/521.html , which is referenced by the 521 code at the att.net/blocks page?

You may have a PC on your network that has been compromised, which may be sending spam as part of a botnet; or, you may have an open relay. It's hard to say. Follow the steps at the URL above to rule those out.

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Went through filling the forms out for the domains ... we'll see where it takes us. –  Eric Fouarge Aug 8 '11 at 21:52

Check RBLs, looks like your IP might be listed in there. I get this from AOL.com every once in a while when a user I CC mail to her home account marks the emails as spam and ends up getting us blocked.

One place to check is here http://www.mxtoolbox.com/blacklists.aspx

Good Luck.

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