Problem and setup are described in this thread.
We too serve users inside the LAN and send and receive mail from the internet. This is why our server is in the LAN.
We have a public IP and a public MX record for our Zimbra server. The server sits on the LAN behind a Firewall/NAT. Port forwarding is used to direct all needed ports (SMTP/IMAP4/POP3/etc.) to the Zimbra server.
We are trying to install the Zimbra server but failing at the MX record check in the install script. The installer checks for an MX record but receives the public IP of the Zimbra server. Since the server has a private IP the check fails and the installation quits.
How can we install Zimbra servers behind a NAT?
Thanks very much!