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Exchange issue

Posted on 2009-02-19
Medium Priority
Last Modified: 2012-05-06
I am learning exchange on the fly here so..... Does this error mean I am being blocked by att ?

      john.doe@sbcglobal.net on 2/18/2009 2:04 PM
            The message cannot be delivered due to a configuration error on the server. Please contact your Administrator.
            <servername.domain.com #5.3.0 smtp;553 5.3.0 flpi118 - n1IK3YSN027926, DNSBL:ATTRBL 521< xxx.xx.xxx.xx >_is_blocked.__For_information_see_http://att.net/blocks>

where xxx = my outside ip address

Question by:txbanshee
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LVL 12

Expert Comment

ID: 23681222
Sounds like the person you are trying to email has their email account suspended or terminated.  You might want to try calling or using an alternative email address if you have one.
LVL 58

Accepted Solution

tigermatt earned 2000 total points
ID: 23681230

That NDR message is indicating that your external public IP is blocked at AT&T on some sort of blacklist.

The most likely issues are that you are either blacklisted, do not have your DNS configured correctly (http://www.amset.info/exchange/dnsconfig.asp) or you are on a Dynamic IP address.


Author Comment

ID: 23682028
Ok thats what I thought I was reading. I submitted to ATT to be unblocked. I don't show up on any blacklist so it must be something att is doing.
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LVL 58

Expert Comment

ID: 23682158

You would want to check you have your DNS set correctly, particularly your SMTP banner and PTR record. However, if other outbound mail works, it's likely to be an issue at AT&T.


Author Comment

ID: 23682195
yeah it seems all other outbound email is doing fine

Expert Comment

ID: 23696459
My client just started getting this same error. We have had business DSL (STATIC IP) starting with Pacbell and grandfathered into sbc, and now AT&T. Honestly their systems are a joke. Every six to nine months for as long as I can remember we get blocked. It always seems to correspond with a new change in their back end. It takes forever trying to get this resolved and always ends up being them. If your on a different ISP the process is even more painful.

To save you a little time go to http://www.mxtoolbox.com and do a diagnostic on your mail server by IP or DNS name. Verify you have your banner and rDNS match up. I would highly recommend having your rDNS and banner resolve to the dns name of your server.

Verify you are not an open relay and resolve that issue if you are.

Setup a SPF record and Geocoding. Not been a requirement in past but this new system may require it.

To help combat spambots, viruses, etc in your firewall rules (Main not software ones on workstations) block all outbound SMTP traffic (TCP 25) except from your mailserver. One client got bit by this years ago. It took almost 4 months to identify this as the problem.

Do all these check prior to contacting AT&T, AOL, COMCAST or who ever else you must deal with. If not the process becomes even harder to resolve and they will inevitably create more hoops to jump through.

I am on the phone with AT&T to resolve this ASAP as a customer of theirs. I will post our findings when complete..

Good luck and beleive me I know your frustration!!

BTW be happy its not AOL they have been by far the worst to deal with. =)

Expert Comment

ID: 23696878
Just like in the past tech support is a joke.

There are two things that can be done. 1st is follow the link att.net/blocks and fill out the form on the 2nd link. Or you can email them directly @ removeme@sbc.sbcglobal.net.

The only other option that it could have been which does not apply to us as we are using our own domain name and mail servers is you must register the DSL id aka user@sbcglobal.net (should have been done to have functioning DSL) and register third party emails ie joe@gmail.com. This allows other email addresses to send using their SMTP servers. Since you use exchange this also probably does not apply to you.

Expert Comment

ID: 23697211
Oh, more info on SPF records can be found at http://www.openspf.org/ 

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