Coexistence with Exchange, Multiple domains,VMWare, different DNS a complex install?

[UnspecifiedId]

Greetings all,

I've read some of the threads in the forum and didn't quite find the answer that I was looking for.

My concept of TCP/IP, DNS and PTR records may be a bit limited.

Environment
2k3 Server Active Directory 172.16.x.1
23k Exchange Server 172.16.x.20
VMWare running Ubuntu with Zimbra (trying to install) 172.16.x.25
Managed Hardware Firewall with external IP address 200.X.X.1
WebHost with Domain Name management

Brief Summary
--------------
Trying to run Zimbra on VMServer(Win2k3 box) on our primary network with a different domain to the network. Eg. work.com is our network with Microsoft Exchange, we wish to put work2.com as a Zimbra server on the same physical lan.

Our Webhost has the MX record ptr which directs through our firewall to our exchange server for the primary domain eg. work.com or mail.work.com

I wish to put work2.com, also hosted by our Webhost having a MX record that points back on the Webhost ie. Apache/with Cpanel etc and as such, I'm wishing to redirect to the VMWare machine

So in pt form

1) WebHost IP has WORK.COM, MX Record points to our static IP 200.X.X.1, goes through NAT to local IP 172.16.x.20 and ends up at our Microsoft Exchange Server (I'm assuming ports 25,110 for the NAT process)
2) WebHost IP has WORK2.COM, MX record points to our static IP eg. 200.X.X.1, goes through NAT to local IP 172.16.x.25 and ends up at our VMWare Zimbra image
So the question is ..
----- with the MX record for WORK2.COM could we specify 200.X.X.1:4025 for NAT to IP 172.16.x.25 ie. Zimbra image ?

During the Zimbra installation it states that the MX Record should have a DNS entry. However our domain is WEST.WORK.COM, if I were to use Microsoft's Active Directory and setup a A PTR record it would be ZIMBRA.WEST.WORK.COM, when really I just want ZIMBRA.WORK2.COM. Ignorance and level of knowledge about to show here...
a) do I setup the A PTR record on the Win2k3 Active directory box eg. 172.16.x.1 as ZIMBRA.WORK2.COM, MX Record of ZIMBRA.WORK2.COM pointing to 172.16.0.25
b) OR setup DNS as a separate entity of the VMWare Ubuntu Image some how binding back to WebHost DNS allowing translation through NAT.

Lastly,
I'm assuming I just perform NAT on the ports that Zimbra requires for external access

eg.
LDAP 389 -> 7389
SMTP 25 -> 7325
POP3 110 -> 7310 etc.

I hope I have communicated what I'm trying to achieve.

Any insights, assistance would be greatly appreciated.

Regards

Gavin

[jholder]

Gavin,
I can't seem to see the question in there

Can you please ask the question, or make it so that simple minds like myself can see it

-john