This is an alternative to the instructions at FilterMailWithSpamAssassinAndProcMail.

The general theory is that incoming mail will be piped through a SendMail "milter", or mail filter, before delivery. The milter I recommend has the nice feature that it only processes mail bound for local delivery, and not mail passing through the server as an intermediate hop in a relay chain. That is, if you're running a backup MX for an associate, mail that is eventually bound for delivery at their server will not be processed. This saves resources on your server and gives your associate the ability to not use SpamAssassin if they chose not to.

Advantages:

• It doesn't require an installation of ProcMail^?.
• It's much simpler than installing and configuring ProcMail^?.

Disadvantages:

• None that I've found.

1. Install SpamAssassin

• If you have PortInstall^? (from the sysutils/portupgrade port):

  portinstall mail/p5-Mail-SpamAssassin

• Otherwise:

  cd /usr/ports/mail/p5-Mail-SpamAssassin; make install; make clean

2. Install the milter

• Download spamassassin_milter.c from http://www.uffner.com/open_source/spamassassin_milter/
• Build libsm. Install the FreeBSDSourceCode if you haven't already. Type cd /usr/src/lib/libsm; make to build it.
• Build the milter:

gcc -L/usr/obj/usr/src/lib/libsm -lsm -lmilter -pthread spamassassin_milter.c -o spamassassin_milter

• Install it: cp spamassassin_milter /usr/local/sbin
• Make an rc.d script to run it automatically at boot. I've named mine /usr/local/etc/rc.d/spamassassin_milter.sh.

#!/bin/sh

if ! PREFIX=$(expr $0 : "\(/.*\)/etc/rc\.d/$(basename $0)\$"); then
    echo "$0: Cannot determine the PREFIX" >&2
    exit 1
fi

case "$1" in
start)
        if [ -x ${PREFIX}/sbin/spamassassin_milter ]; then
                ${PREFIX}/sbin/spamassassin_milter -p unix:/var/run/spamassassin_milter.sock &
                echo -n ' spamassassin_milter'
        fi
        ;;
stop)
        killall spamassassin_milter && echo -n ' spamassassin_milter'
        ;;
*)
        echo "Usage: `basename $0` {start|stop}" >&2
        ;;
esac

exit 0

• Make the rc.d script executable: chmod a+x /usr/local/etc/rc.d/spamassassin_milter.sh
• Start the milter: /usr/local/etc/rc.d/spamassassin_milter.sh start

3. Configure SendMail

Add this near the end of your LocalSendmailConfiguration:

INPUT_MAIL_FILTER(`SpamAssassinFilter', `S=unix:/var/run/spamassassin_milter.sock')
define(`confMILTER_LOG_LEVEL', 7)

4. Return to FilterMailWithSpamAssassin to finish up.

-- KirkStrauser - 03 Jul 2003