Need abuse/postmaster contact for AT&T to resolve IP block

A few of our exchange IPs get blocked intermittently, but only by ATT. Ips are clean, no issues, we’re diligent about finding and fixing these types of issues as it has a large impact.

It would be very helpful to know why the IP below got blocked so we can find and fix the problem to prevent further listing. We have a few ips in rotation and some have no issue. It’s a “blind” listing, so we only find out about it when customers complain that they getting blocked. #< #5.3.0 smtp; 553 5.3.0 flph399 DNSBL:ATTRBL 521< >_is_blocked.__For_information_see_> #SMTP#

Any info/help would be most helpful.

Many thanks, Postmaster

Interestingly, your mail to the nanog list went to my spam folder, rather
than my nanog folder (I'm using gmail or domains for my mail.) That rarely

Gmail here, went to my Inbox.

Try posting that to the mailop list.
I had been having trouble with for about a month, and I filled out
the form at 3 times with no response.

I posted to mailop a few days ago and they resolved the issue within an

...then a few days later I received the response to the form that my IP had
already been unblocked. Even though they say they will get back to you
within 2-3 days, it's more like 10-14.