I am running an XServe, and setup my old G4 as a Zimbra test server.
I've mapped my cable IP in the DNS records of one domain on my XServe for testing purposes.

If I 'ping' g4mail.testdomain.com, I get the correct IP address.

If I telnet to g4mail.testdomain.com on Port 25, I can see the server responding.

I've mapped ports 110 (POP), 143 (IMAP) and 25 to the G4 box, but my problem is that from my XServe, I am unable to communicate with the Zimbra mail server to send it some emails.

Am I missing a port here, that the two servers need to talk on..?