Web servers and hostnames etc

[CreepinJesus]

Ok, just a quick question. Unfortunately, it requires some explaining/setting up.

I have two websites running from an IIS7 server at home, plus an email server on a separate machine.

Port 80 of the web server, is for the websites (obviously). These two websites are 'filtered' using hostname bindings in IIS7 - both are running on the same port on the same machine, but if I get to this IP address requesting abc.com (for example), I get the abc.com site. If I request 123.com, I get the 123.com site. This works very well.

However, the email server also runs a webmail interface (it's Zimbra) from its own port 80. My current setup is to forward mail.mydomain.com to port 10000 of mydomain.com, which is then passed to port 80 of the email server using my router.

My question is (the wait is over), can I forward all port 80 traffic from my router to both the web server and the email server, then somehow use the same kind of binding/hostname on the email server so that mail.mydomain.com goes there? It's running on an Ubuntu 8.04 system (horrible), so bear in mind that anything that sounds simple will take at least a day to fix .

Thanks.