Integration SpamAssassin with Postfix

This file contains information on how to integrate SpamAssassin with Postfix
for incoming mails.

1. Set SpamAssassin to start after booting the system

Edit /etc/defaults/spamassassin and set SpamAssassin to start after a reboot.

2. Start SpamAssassin

/etc/init.d/spamassassin start

3. Create a filter user.

adduser --disabled-password --disabled-login --gecos "Postfix Filter User" filter

4. Create the filter script.

Under ~filter, create filter.sh:

#!/bin/sh
/bin/cat | /usr/bin/spamc -f | /usr/sbin/sendmail -i "$@"
exit $?

Be sure to chmod it to 750, at least.

A more complete example can be found under /usr/share/doc/spamassassin/examples

5. Set /etc/postfix/master.cf

It must contain the following lines:

localhost:smtp          inet    n       -       -       -       -       smtpd
<external.ip>:smtp      inet    n       -       -       -       -       smtpd
  -o content_filter=filter:

[...]

filter    unix  -       n       n       -       -       pipe
  flags=Rq user=filter argv=/home/filter/filter.sh -f ${sender} -- ${recipient}

6. Reload postfix

As root, exec:

#> postfix reload


That should be it.

Aug 2003, Jesus Climent