====== ClamSMTP + Bogofilter ======
<code>
smtp      inet  n       -       n       -       -       smtpd
  -o content_filter=clamsmtp:127.0.0.1:10025
  -o receive_override_options=no_address_mappings
# clamsmtp
clamsmtp        unix    -       -       n       -       16      smtp
        -o smtp_send_xforward_command=yes
# injecting back
127.0.0.1:10026 inet    n       -       n       -       16      smtpd
        -o content_filter=
        -o receive_override_options=no_unknown_recipient_checks,no_header_body_checks
        -o smtpd_helo_restrictions=
        -o smtpd_client_restrictions=
        -o smtpd_sender_restrictions=
        -o smtpd_recipient_restrictions=check_recipient_access,pcre:$config_directory/
rcpt-bogofilter.pcre,permit_mynetworks,reject
        -o mynetworks_style=host
        -o smtpd_authorized_xforward_hosts=127.0.0.0/8
bogofilter        unix  -       n       n       -       -       pipe
  flags=R user=bogofilter argv=/usr/local/etc/bogofilter/postfix-filter.sh -f ${sender} -- ${recipient}

</code>

  * rcpt-bogofilter.pcre
<code>
# first match!
#/^spamlover@example\.org$/    OK
/.*/                    FILTER bogofilter:
</code>

===== postfix-filter.sh =====
<code>
#!/bin/sh

FILTER=/usr/local/bin/bogofilter
POSTFIX="/usr/local/sbin/sendmail -i"
export BOGOFILTER_DIR=/usr/local/etc/bogofilter

# Exit codes from <sysexits.h>
EX_TEMPFAIL=75
EX_UNAVAILABLE=69

cd $BOGOFILTER_DIR || \
    { echo $BOGOFILTER_DIR does not exist; exit $EX_TEMPFAIL; }

# Clean up when done or when aborting.
trap "rm -f msg.$$ ; exit $EX_TEMPFAIL" 0 1 2 3 15

# bogofilter -e returns: 0 for OK, nonzero for error
rm -f msg.$$ || exit $EX_TEMPFAIL
$FILTER -p -u -e > msg.$$ || exit $EX_TEMPFAIL

exec <msg.$$ || exit $EX_TEMPFAIL
rm -f msg.$$ # safe, we hold the file descriptor
exec $POSTFIX "$@"
exit $EX_TEMPFAIL
</code>