Unblock / Delist IP request
We are getting the following error on emails sent to att.net addresses:
553 5.3.0 flpd596 DNSBL:ATTRBL 521< 188.8.131.52 >_is_blocked.For assistance forward this email to firstname.lastname@example.org
I've tried the http://rbl.att.net/block_inquiry.html and emailed email@example.com with no response. Also verified we aren't listed on any other blacklists through mxtoolbox.
Can you help us?