We currently have two networks running on two separate IP address spaces. We had to move our exchange server from one to the other. Now we are getting failed reverse DNS lookup NDRs.
Our MX records are showing the correct IP address, when I ping the mail server from outside the network the correct IP address shows up. However, when I use mxtoolbox.com's smtp tester I get the error that SMTP reverse banner check is failing and we are getting numerous NDRs due to lack of reverse DNS.
What am I missing?
Please let me know what information I need to provide to help you solve this issue.