Norman,

You are correct, SpamFilter is designed to handle incoming email only. Outgoing email should still be processed by your existing SMTP server.

There are several ways to configure the email flow to accomodate your environment:

Internet ---> Firewall/Router ---> SPAMfilter -->VPOP3 mailserver

The simplest solution, if the firewall allows it, is the following.

Configure your firewall to accept internet email traffic on port 25, and have it perform port translation to pass it on to SpamFilter on a different port, say 26.
Configure SpamFilter to listen on port 26, which will allow it to accept email coming from the firewall. Have SpamFilter forward email to port 25 on your existing SMTP server
Leave your SMTP server's configuration unchanged, always listening on the same IP your customers have and on port 25. This way no users will have to make any changes, and they will still use your existing SMTP server for their outgoing email.

This would be the email flow:

Internet (25) --> Firewall -- (26) --> SpamFilter --(25)--> Your SMTP server

Most non-home-style firewalls should be able to perform the port translation required.

If the above is not an option, bind two different IPs to the NIC on your server. Again do not alter your existing SMTP configuration, and have SpamFilter listen on port 25 of the 2nd IP address. Then have your firewall forward email traffic (to port 25) on that 2nd IP. SpamFilter will then forward it to the IP of your SMTP server. In this way too no users will have to make any changes, and they will still use your existing SMTP server for their outgoing email.

If that also is not an option.. well, you could add your own class C's that the users are on to the whitelist in SpamFilter, so they will be allowed to relay using SpamFilter.

Roberto F.
LogSat Software