NAT for IIS SMTP virtual servers--rule writing help please.

We've set up a Windows box with a bunch of SMTP virtual servers in IIS. Unfortunately, while each SMTP server listens on it's own assigned address, they ALL send on the default IP of the server's NIC. This is not the behavior we want.

 

 

Looking through some of the iRules here we've gotten the impression that we might be able to use an iRule to NAT the outbound mail based on the name of the server as sent in the EHLO line of an SMTP conversation, however we're unfamiliar with iRules. Anybody who can help us code this? Here's a table of info:

 

 

"Public" IP SMTP-Server-Name "Private" IP

 

192.168.0.1 default NIC IP 10.0.0.1

 

192.168.0.2 smtp.domain1.org 10.0.0.2

 

192.168.0.3 smtp.domain2.org 10.0.0.3

 

etc...

 

 

So, when outbound traffic from the server originates with IP 10.0.0.1, we want to check the EHLO line for the SMTP server name (smtp.domain1.org) and NAT the outbound traffic to the appropriate public address (192.168.0.2) instead of the default, 192.168.0.1

 

 

Any help would be appreciated.