AT&T is saying I my IPs are blacklisted, but when I check they are fine
Over the past week or so suddenly anything going to an AT&T hosted email is bouncing back saying the IP is blacklisted. Here is a sample:
Delivery for [email scrubbed] to [email scrubbed] has bounced. Reason: Remote host said: 553 5.3.0 alph747 DNSBL:RBL 521< x.x.x.x >_is_blocked.For assistance forward this error to firstname.lastname@example.org
I have checked DNSBLs site and I get all green check marks. The users have SPF records and DKIM records. I am out of ideas.
The irony of a very false positive is my mail server gets slammed with spam emails from AT&T email accounts.
The abuse_rbl sounds like it is useless, one customer has been waiting about a week and no response.