Scrub and forward email

I have a client who wants me to receive all his email on my Virtualmin server and run it through SpamAssassin and ClamAV before forwarding it on to his inhouse mail server. His goal is to reduce traffic through his internet connection and to not have to install spam and antivirus on his server. Any thoughts on how to set this up through Webmin/Virtualmin?

At work I have a server which runs ASSP then forwards all scrubbed e-mails to my webmin/virtualmin server. There are so many variations as to how you want to setup ASSP. I use to ran spamassassin,razor,clamav, greylisting to stop spam but now I prefer using ASSP. My spam dropped to almost nothing.

Here’s an excellent how-to site:

http://www.howtoforge.com/assp_clamav_postfix_debian_etch