4-C: RAZOR

apt-get install razor

#Added the following to spamassassin's local.cf file:
echo "razor_config /etc/razor/razor-agent.conf" >> /etc/mail/spamassassin/local.cf

#Then execute the following two commands:

razor-admin -d -home=/etc/razor -create
razor-admin -d -home=/etc/razor -register

#You can check the logs on /var/log/spamd/current for razor errors. Sometimes there are directory issues that can be easily corrected by symbolic links.