Changed NIC now No MX record found

[skeating]

Hello
One of my Ability mail servers was behind a pfSense firewall, which the Abillity used NAT to get to the outside. I have since removed the Ability from behind the pfSense, and given it the same public IP it had when behind the pfSense. Now when I try to send email to two domains, I get the message MX record not found. The Ability is still pointed at the same DNS as before. The two domains always went through with no problems. I have restarted the Ability server, thinking the IP change might something to do with it, but no luck. One of the reasons I removed the Ability server from behind the pfSense was Gmail would always reject the email sent. Now Gmail accepts the email, but the two domains I sent to before cannot be found. Would a /flushdns cure this?

[Code Crafters]

Try using the MX Lookup and Test DNS tools from the Tools page of the settings for the domains you're concerned about to see what the results are.

[skeating]

I have done the MX lookup and DNS lookup, and all is fine. Is there something inside of the Ability server that I need to check or reset since making the changes? It seems strange that the domains I was having trouble resolving are now fine, and the ones I used everyday can not be resolved.

[Code Crafters]

Are you using your ISPs DNS or other internet based DNS server? Or are you using an internal DNS server?

[skeating]

The problem was resolved When I was asked to check the Outgoing Mail section of the Ability Mail Server. Sure enough, the DNS IP had not been changed and was still pointing to the private IP for the pfSense firewall. Once I changed that to the public IP for the DNS, the problem was solved.