I have an internal server that I want to setup with Zimbra.
It is currently running with Sendmail in the following configuration.

- The server is connected through a ADSL Model and port 25 is forwarded to it.
- The ADSL is on a static IP Address.
- The ADSL Modem static IP Address resolves to mail.DOMAIN.com
- eth1 is connected to the ADSL on 192.168.1.x
- eth0 is connected to our LAN 192.168.0.x
- The internal domain is internal.DOMAIN.com.au
- The server is called FQDN: server.internal.DOMAIN.com.au
- Web server for internal
- Samba Server for internal

Zimbra is extreemly pedantic about the FQDN and server name, which looks like this configuration will be difficult to set up.

What is the reccomended configuration for an internal server?