If you run IIS4 (on NT4) or IIS5 (on Win2K), SMTP is installed by default,
and will, again by default, grab port 25 - for ALL IP addresses on the
system.

For our site, there are two IP addresses assigned on a single NT image, one
for the listserv, and one for the web, at list.feat.org and www.feat.org
respectively. We have been running it this way for two years. You cannot
run MS-SMTP and the Listserv on a system with only one IP address.

Presuming that have already, or know how to assign multiple IP addresses to
an NT system, the remaining thing to do is assign services to particular
IPs. In the Internet Services Manager applet (using the dreaded Microsoft
Management Console), you can select the properties for any given service,
in which there will be a drop down list box that will have the IP addresses
that can be assigned.

The default is "Any Assigned", which in the case of SMTP, will aquire port
25 on all IPs assigned to the system. Select the IP address that you want
SMTP to list on, which will turn off the allocation of port 25 for any
remaining IP addresses.

You must shutdown the service to actually get SMTP to release the port (not
the logical service presented by MMC), but I would recommend rebooting the
box. Also do not forget to appropriately configure the listserv to listen
on the *other* IP address.

Note that MS-SMTP is a required component of IIS should you want the
website to be able to send administrative email messages, or have the some
of the server side messaging applets run.

Michael McIntire