Temporarily running a server as a router

[Gizmo2003]

ACK! Our Cisco 2600 bit the dust this weekend (magic flash error), and I have installed a W2K Server to temporarily run as a router. It has been installed and is routing information back and forth from network to internet. Where I am having troubles is as follows:

Our router had inside source NATs so that the external email would be passed on to the internal address of our email server (SMTP and webmail), and I am having a hard time getting windows to pass mail from the temporary W2K server to the email server.

More specifically, the router send email destined for 209.217.x.x to our internal address of 192.168.5.x, and for the life of me (or maybe lack of sleep...she went down at midnight last night, and I have awoke from a catnap after a long night of emergency troubleshooting before calling it dead and getting the server up to route) I cannot get my server to do this. I have not turned NAT on, as if I do this, it is spewing crap to my internal clients...is there any way to emulate the routing on the server so that it is not going to chug things down?

Thanks,

Gizmo

 

[telepath]

Have You tryied to install a software firewall? I never used those for email, only to Internet traffic but I have seen SMTP and pop3 functions on some of them and most of them have trial versions of 30-90 days wich should be enough while yoou repair the router.
Ihope this helps

 

[DaShard]

Did you use 2 NIC cards?

 

[Gizmo2003]

3 actually - one for our public IP, one to our DMZ and one to our VPN concentrator...

Gizmo