Procmail filtering with Plesk and Spamassassin

On a typical Unix Plesk installation, you will find your mailbox settings under this folder

/var/qmail/mailnames/(yourdomain)/(yourmailuser)

Each mail account folder will have a directory listing similar to the following:

drwx------    5 popuser  popuser      4096 Apr  4 13:55 .
drwx------    5 popuser  popuser      4096 Mar 23  2006 ..
-rw-------    1 popuser  popuser       329 Mar 23  2006 .qmail
drwx------    2 popuser  popuser      4096 Nov 15 12:00 .spamassassin
drwx------    2 popuser  popuser      4096 Mar 23  2006 @attachments
drwx------    8 popuser  popuser      4096 Feb  2 21:17 Maildir
-rw-------    1 popuser  popuser     12288 Feb  2 19:21 auto-whitelist
-rw-------    1 popuser  popuser     12288 Apr  4 13:55 bayes_seen
-rw-------    1 popuser  popuser     12288 Apr  4 13:55 bayes_toks
-rw-r--r--    1 root     root           61 Mar 23  2006 user_prefs

If you have Spamassasin enabled for the mail account, you will see the .spamassassin file and the bayes files. Otherwise, you can create these files and invoke Spamassassin for each mail account required.

These steps can also be helpful if you have disabled Spamassassin under Plesk but you would like to use it on new mailboxes.

First, you will need to modify the .qmail file. Plesk will create this file with the following contents:

| if [ -z "$SA" ]; then export SA=1; /usr/local/psa/bin/psa-spamc -f -u sales@mydomain.com -U /tmp/spamd_full.sock > spamcheck$$; /var/qmail/bin/qmail-local "$USER" "$HOME" "$LOCAL" "" "" "$HOST" "$SENDER" "$DEFAULT" < spamcheck$$; retval=$?; rm -f spamcheck$$; [ $retval = 0 ] && exit 99; exit $retval; fi
| true
./Maildir/

Using your favorite editor, open .qmail and change it to the following

| preline /usr/bin/procmail -p -m .procmailrc

This instructs qmail to call procmail each time a message is delivered into your mailbox. From here, procmail will handle the invoking of Spamassassin and other mail sorting.

Next, create a file called .procmailrc and paste the following into it.

# Run SpamAssassin
:0fw
| spamassassin

# Move spam to the .Junk folder
:0:
* ^X-Spam-Status: Yes.*
./Maildir/.Junk/

# Let other mail go through
:0:
*
./Maildir/

The procmail file can give you tons of flexibility on dealing with mail as it arrives. Notice the line ./Maildir/.Junk/ which is the target folder to move spam into. Depending on what email client you use, you may not have this folder in your Maildir folder. Check your Maildir folder and see what works best for you, which may be .Spam or .Trash

Finally you will need to have a user_prefs file in your mailuser folder. This file contains simple settings for Spamassassin that are for each mail user.

required_hits   7
rewrite_subject 1
subject_tag     *****SPAM*****
rewrite_header Subject ****SPAM(_SCORE_)****

It is important to note that these settings change with different versions of Spamassassin. You will need to determine the version you have and the appropriate settings values.

Now you can easily copy these three files to other mailboxes and enable Spamassassin on any mail account.

Update
If you are interested in using a script to generate the .qmail and .procmailrc file server wide, see the article Plesk Default Settings Script for qmail and procmail