I need help installing Zimbra for multiple networks. I have gotten it to work just fine on a single network but we need our email server to stratle two different networks.

eth0 -> internet side with local clients who can surf and email etc.
eth1 -> private secure network that just needs access to send and receive email.

I am using the latest version of Zimbra CE and running RHE 4.0. If anyone can offer some assistance I would really appreciate it.