Question about host name and FQDN

[StevekTN]

I've got Zimbra setup and everything seems to be working. I'm just not sure that I have everything configure correctly as far as internal network naming and external/internet. Here's my setup:

External/Internet:
Web and mail are currently host by our ISP. Domain would be "domain.com" for web and email.

Internal:

We have a mix of PCs and Macs. We have an Apple Xserv setup as an Opendirectory Master / Samba PDC. The Xserv also handles DHCP and DNS for our internal network. FQDN = xserv1.domain.private

Zimbra is setup on a Ubuntu computer. This computer's IP is set in the xserv's DNS zone and set as "mail server for the zone". FQDN = zim.domain.private

NAT / Firewall is computer running Fedora. FQDN = serv.domain.private

All of our users are used to their mail being addressed to user@domain.com. When I make the change over, I would like to keep it that way. In the Zimbra server admin I have setup the domain "domain.com" with "Relay MTA" setting under Global set to our ISP's smtp server. For my test user, I have setup and external account to check POP for user@domain.com under the "Accounts" tab.

Everything seems to work, although I haven't really tested with much use yet. Does my setup seem correct? Is there a more preferable way of doing things? Thanks for any comments of insights.

Steve