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Email from our SBS Exchange 2003 server gets rejected by any worldnet.att.net domain

Posted on 2008-06-18
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Last Modified: 2010-04-21
Recently our domain has been getting rejected from any one of the dozen or so domains out there that are part of AT&T (bellsouth, snet, sbc, etc, etc).  Up until last Friday eveything worked just fine, and since then, chaos.  While my company maintains our own Exchange server, we have a number of outside users around the country (not to mention customers) that rely on AT&T DSL, so our office is in the lurch.  According to at least one AT&T customer rep, there were some changes made to AT&T mail servers that tightened security, but I don't know how reliable that really is.

Anyway, we own several domain names which point back to our Exchange server and all but one of the A and MX records for these domains are kept at Godaddy.com.   The lone standout is instead kept with our ISP.  All of the MX records at Godaddy point back to the domain kept at our ISP as well.

So far, it seems that I can send email to any of the AT&T sites if I go into Active Directory, select one of our users, and change their primary email address to use the domain that is kept with our ISP.  If a user has primary email from a domain hosted at Godaddy, I get rejections.  Nothing has changed at our end, nor at Godaddy.  I've double-checked to make sure there is no open-relay issues and to the best of my knowledge we aren't one.

I have since sent a request to at&t to get off of their blacklist, and for some of the AT&T domain it seems to have worked.  But other AT&T domains are still rejecting our messages.

I don't know if I'll get a perfect answer for this, but if anyone has run into trouble with AT&T domains before, perhaps I can get a bit more enlightenment for it. :)

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Question by:jerry_higgins
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by:Andres Perales
ID: 21814990
Was there a link in your non delivery reports from ATT, I saw another like that earlier and theirs had a link with information about mail rejections?

have you checked to see if you domain names have been blacklisted?
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Author Comment

by:jerry_higgins
ID: 21815026
Yes, I've checked blacklists, and none that i've looked at indicate that our name or IP address are blacklisted (though I think AT&T maintains their own internal list, if I'm not mistaken)

Here are some of the more common rejections I've seen:

The message cannot be delivered due to a configuration error on the server. Please contact your Administrator.
#5.3.0 smtp;553 5.3.0 nlpi008 - m5HBJ1pj030757, DNSBL:521< 69.95.XXX.194 >_is_blocked.__For_information_see_http://att.net/blocks>

There was a SMTP communication problem with the recipient's email server.  Please contact your system administrator.
            <mail.rfainternational.com #5.5.0 smtp;550-69.95.XXX.194 blocked by ldap:ou=rblmx,dc=att,dc=net>
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Andres Perales earned 250 total points
ID: 21815155
The link in the non deliver reports takes me here, have you visited the site?

http://worldnet.att.net/general-info/block_inquiry.html

maybe that can help direct from Att
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Expert Comment

by:Press2Esc
ID: 21821902
1) Specifically, check your PTR (rDNS) for valid records...
-   You have a AT&T Static IP assigned to your mail server(s)?

2) Send email to postmaster and ask specifically WHY (what infraction) your domain(s) emails are violating which are causing AT&T to block your emails - and fix the problem.  (see item 1)

P2E
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Author Closing Comment

by:jerry_higgins
ID: 31468486
Thanks, I did go through that link, which fixed the issue and had since come to the conclusion that AT&T is trigger happy with their blacklists.  Perhaps matters are complicated by the fact that we have to deal with customers & vendors whose email domains originate in countries that are known to breed spam en masse.

Thanks anyway!
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