2 Email servers on same DMZ cant send to each other

[akacamper]

I have 2 email servers on my DMZ(172 network). They both have to connect to the (192 network) to go out to the internet. Both servers can send and recieve email from outside the company. Both email addresses can recieve mail from there address. Last i can ping from 1 email server to the other. They both have separate domain addresses.

The problem is when i try to send a email from
camper@a.com to camper@b.com or
camper@b.com to camper@a.com

I get an error (Deferred: Connection timed out with mail.b.com or mail.a.com) and the email is never recieved.

I am using a cisco 525. Maybe i am just missing a access list for my DMZ or inside that will allow them to talk to each other. does anyone have any suggestions?

 

[folken]

Are your servers pointing to an internal or external DNS server? If it is internal make sure there is a correct entry for both servers.
When in doubt blame dns... it seems to be the issue in most email problems, lol.