AT&T DNS Block - Suggestions to fix this?

[Franseza]

We are having a SBS 2003 server running at out office with several client workstations. Everything was working fine since a year but yesterday suddenly few of our users started getting couple of DNS Blocks from AT&T with the following message:

“The message cannot be delivered due to a configuration error on the server. Please contact your Administrator.
<lifetime-media.com #5.3.0 smtp;553 5.3.0 nlpi090 - m8QG9RbC031621, DNSBL:521< IP ADDRESS
>_is_blocked.__For_information_see_http://att.net/blocks>”

The setup is on Static IP, then what could be the problem? Any ideas?

[CoYoTeA]

Due to some security reasons, AT&T puts some users on their Blacklist. I’m not sure but you guys might have done something wrong OR by mistake AT&T might have put you in Blacklist which resulted in this problem.

You should try contacting AT&T for the same. They will help you out for sure.

[T.J.]

You are right CoYoTeA but not completely. Actually they might have not put them on Blacklist but many times ATT blocks inbound port 25 and I guess this has happened because they are using inbound email and this company does not have a business class DSL account. You guys should look in for this.

[FRIESEN]

Well I found an Article in ATT knowledge base which describes exactly your problem. You should check out the same, I’m sure it will help you. Here it is: http://worldnet.att.net/general-info/bls_info/521.html