The block message is 521 DNSRBL: Blocked for abuse

Michael Schuler mike at
Wed Sep 18 16:53:59 UTC 2013

My experience in the past is that it can take a good amount of time for ATT to remove you from their black list.  It's been as short as 24 - 48 hours and as long as a couple weeks and required follow up contact with support.  They're a big company and they get a lot of requests.  I've not dealt with Network Solutions or their RBL list as far as how to get whitelisted.  But it sounds like they manage it in a way where the recipient has to accept email from you.  It's probably not practical but can you contact the recipients on Network Solutions via another method to have them whitelist you? 

>From the sounds of t the IP address you purchased was previously used by a spammer and now you're paying the price for it.  Perhaps there are contacts on this list from ATT/Network Solutions that can contact you off list to help you resolve that. 

Good luck!

Mike Schuler
a guy

On Sep 18, 2013, at 11:07 AM, NANOG <NANOG at> wrote:

> We recently purchased new IP addresses from ARIN, with plans on using one of them for our external and internal email delivery.  We set up a reverse lookup and a SPF record for the newly purchased IP to prevent being classified as spam.  We tested the functionality of the PTR and SPF record successfully using varies internet tools like,, and  Unfortunately, when we send emails to any AT&T or Network Solutions hosted email we are being block as a spam abuser.  I checked varies spam database tools and our IP addresses are not listed, but we are still being blocked by both AT&T and Network Solution.  The block message is 521 DNSRBL: Blocked for abuse.  In an attempt to be proactive, I contacted Network Solution and was told that each recipient would have to request we be whitelisted, and AT&T directed me to an online form that I submitted to be removed from the blacklist.  Unfortunately, we are still not able to send emails to either AT&T or Network Solutions hosted emails.  Our mail server IP address is, which resolves to  Does anyone have any suggestions on where to turn next?  Is it possible they are blocking us based on old information from the previous IP address block owner?  Any help tracking this down would be appreciated.
> Derrick Wash
> Microsoft Systems Administrator
> ABC Supply Company Inc
> Office: (608)368-2214
> Fax: (608)363-0214

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