Hello again EE!
A client of mine recently upgraded their ATT service which included the need to reassign IP addresses. I didnt receive any preliminary cutsheets which would contain the new addresses so I had to make all of the changes onsite quickly including the Firewall (NAT, ACL) and DNS (Forward and Reverse). Everything was checking out ok, mail was flowing, internet works, VPN works, etc. However.... now I have delayed emails to AOL, Windstream, and a few others. They are all complaining about a reverse DNS. To put a timeline on this project, the cutover was 7 days ago. 4 days ago I contacted ATT to make sure they were delegating DNS to our nameservers, which they were not, but they are now. After they updated their changes, about an hour or so later instead of seeing no PTR for our IP I was seeing their standard "in-arpa" PTR. The next day I am now seeing the proper PTR when using MXToolbox.com but some other sites report no PTR or still show the "in-arpa".
I am at my wit's end here because everything that I have control over seems to be set up properly but yet the emails will still not leave the queue and many are expiring. the client is not happy but I don't know what to do. Any idea what the issue is and what I can do to fix it? I can supply the IP via PM if that will help.