Help with an email error and NDR...

[spotdog14]

We have an ATT T-1 at work with an Exchange 2003 server. We seem to be getting these errors for the last few days and I cannot figure out what the problem is....

Your message did not reach some or all of the intended recipients.

      Subject:	FW: Case No. U-15645 Discovery Responses to Abate
      Sent:	2/24/2009 10:32 AM

The following recipient(s) cannot be reached:

      xxxx@sbcglobal.net on 2/24/2009 10:32 AM
            The message cannot be delivered due to a configuration error on the server. Please contact your Administrator.
            <smtp.xxxx.com #5.3.0 smtp;553 5.3.0 flpi100 - n1OFXS4b032506, DNSBL:ATTRBL 521< 12.18.xxx.xx >_is_blocked.__For_information_see_http://att.net/blocks>

Any ideas?

 

[KaosDG]

Looks like your server is on a DNS Blacklist.

Did you go to the link in the NDR? (http://att.net/blocks)
http://worldnet.att.net/general-info/521.html - for your specific error code

Also run your server's IP here: http://www.spamhaus.org/sbl/index.lasso

 

[spotdog14]

Looks like your server is on a DNS Blacklist.

Did you go to the link in the NDR? (http://att.net/blocks)
http://worldnet.att.net/general-info/521.html - for your specific error code

Also run your server's IP here: http://www.spamhaus.org/sbl/index.lasso

Yes I did, they didn't provide that much information. I ran the IP through Spamhaus:

IP Address Lookup

12.18.xxx.xx is not listed in the SBL

12.18.xxx.xx is not listed in the PBL

12.18.xxx.xx is not listed in the XBL




If the IP you are checking is not in our database, but you are receiving bounce messages saying it is, then it is probable the IP has been removed from our database but DNS servers around the internet have not yet updated. In this case, wait 1-2 hours and the blocking should clear by itself.

This lookup tool is for manual (non-automated) lookups only. Any perceived use of automated tools to access this system will result in firewalling or other countermeasures.

I have also filled out the ATT form for removing my IP from the black list twice. They say it can take up to two business days.... thats a long time for a business to not be able to send email to some people.

 

[KaosDG]

well, aside from requesting to be removed, you need to investigate why you got put on in the first place.

Generally normal volume e-mail traffic won't get you put on a blacklist.

Make sure that only your email servers are able to send out (block everyone except email servers from using smtp at the firewall, etc) and look for any infected / hijacked PCs on your networks

 

[spotdog14]

well, aside from requesting to be removed, you need to investigate why you got put on in the first place.

Generally normal volume e-mail traffic won't get you put on a blacklist.

Make sure that only your email servers are able to send out (block everyone except email servers from using smtp at the firewall, etc) and look for any infected / hijacked PCs on your networks

That is my next step. I have emailed ATT and they say that I am not on the block list. I am not usually the one that deals with the email server, its kind of like Greek to me. But he seems to be incognito today so that is why it has fallen on me. I will check with the firewall and see if anything strange is going on.

Thanks for the advice!