A subject that gets a lot of discussion on the ISAserver.org Web boards and mailing list is the SMTP Message Screener. The reason for this is that the Message Screener takes a bit of tweaking to get working right. The SMTP Message Screener does provide functionality that you would otherwise have to obtain from third party solutions. The good news is that it does indeed work!
Configuring ISA Server 2000 : Building Firewalls for Windows 2000
By Deb and Tom Shinder
The IIS 5.0 SMTP server will act as a mail relay and forward mail for your domain to the mail server. The ISA Server and the IIS 5.0 SMTP server (with the Message Screener installed) communicate with each other via DCOM to provide Message Screener functionality.
While these configurations are possible, making them work quickly and easily is not.
In this article we'll go over the procedures you need to carry out to make the SMTP Message Screener work using the simple configuration.
Install the SMTP Message Screener
Enabling the ISA Server SMTP Application Filter
We're not going to go into the configuration of the SMTP application filter in this article. We'll cover that in a future article at the Web site.
Configuring the Internal IIS 5.0 SMTP Server
This SMTP server will be configured with a Remote Domain that will only accept mail for your mail domain. This prevents spammers from using your server as a relay. The Remote Domain will be configured to relay mail to your Exchange or other SMTP server. The Exchange Server will need to be configured to accept mail from Message Screener SMTP Server.
Configuring DCOM Permissions