This arcticle desribes how we can implement custom mail filtering in a plesk9 server having postfix as the MTA. This can be used for mailfiltering tasks like moving over spam messages to a spam or .Spam folder at delivery time etc.This is only a single use that i have described here..but you can devise do any filtering that you can do with the procmail Mailfilter and its filtering language on a per mail account basis

WARNING: you will replace the custom plesk virtual mail delivery agent..and in turn lose all abilities to manage spam filtering and other mail related functions like grouping from the plesk web interface. Attempt this only if you dont have problems managing things from the commandline.Please backup /etc/postfix folder before you attempt this!

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1. Change the default virtual transport that is called whenever a mail for a virtual user has to be delivered

postconf -e "virtual_transport = procmail"

postconf -e "procmail_destination_recipient_limit = 1"

2. Define the procmail transport in master.cf as below.Please note it is a single line!

procmail unix - n n - - pipe flags=RO user=popuser argv=/usr/bin/procmail -t -m USER=${user} RECIPIENT=${recipient} /etc/postfix/procmailrc.common

3.Create /etc/postfix/procmailrc.common with following content:

========

:0
* RECIPIENT ?? .*@\/.*$
{ DOMAIN = "$MATCH" }
#added RECIPIENT variable and we extract domain name
HOME="/var/qmail/mailnames"
MAILDIR="$HOME/$DOMAIN/$USER/Maildir"
DEFAULT="$MAILDIR/"
#each user will set his own log file
VERBOSE=ON
LOGFILE="/var/log/procmail/proclog-$USER-$DOMAIN"
NL="
"
WS=" "
SWITCHRC="$HOME/$DOMAIN/$USER/.procmailrc"
=======

Enable logging only in the initial phase for troubleshooting ease.Once you find everything is working as intended.Comment out verbose and logging in the above file

Thats it!. no you can define a per user procmail filter at each users mail account in the file .procmailrc

eg: /var/qmail/mailnames/gnusys.net/anoop/.procmailrc

Here is a sample .procmailrc that i used to get spam mails moved into .Spam folder

=====

# send mail through SpamAssassin
:0 fw
* < 256000
| /usr/bin/spamassassin
#filter
:0 H
* ^X-Spam-Status:.*Yes
.Spam/
=====

Problems in this.Contact me at anoop[at]gnusys[dot]net

Tags: plesk, postfix.procmail

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