clamassassin is a shell script for filtering an email message through ClamAV, using either the command-line scanner clamscan or the client clamdscan. It adds message headers according to the disposition of the mail in a manner similar to Spamassassin, making it convenient to call through Procmail.
Sample procmailrc file
An /etc/procmailrc file passing mail through clamassassin followed by spamc.
DROPPRIVS=yes :0 fw | /usr/local/bin/clamassassin :0: * ^X-Virus-Status: Yes $HOME/Virus :0 fw | /usr/local/bin/spamc -U /var/run/spamd.socket :0: * ^X-Spam-Status: Yes $HOME/Spam