Spamassassin is a tool for helping identify spam in incoming email. Configuring spamassassin is fairly straightforward:
:0fw
| /usr/pkg/bin/spamassassin -P
:0:(the above will put the spam into "mail/caughtspam" in your homedir.)
* ^X-Spam-Status: Yes
mail/caughtspam
X-Spam-Flag "YES" | ? "/cs/lib/rcvstore +spam"
Spam email will be identified with a '*****SPAM*****' tag added to the Subject line of email that Spamassassin believes is spam.