How to : SpamAssassin with Courier mail server

Intro

We asked me to install a antispam solution on a courier-mta mail server. Since dspam project seems to be inactive I choose to give a shot to one of the most known solution : SpamAssassin.

Configuration

Maildrop

We will use maildrop MDA in order to redirect mail to our SpamAssassin filter.

maildrop activation

echo "|/usr/bin/maildrop" | sudo tee -a /var/vmail/mydomain.net/shebang.thedolphins/.courier

/etc/maildroprc

import HOME
import USER
if ( /^To: .*shebang.thedolphins@mydomain\.net.*/ && $SIZE < 256000 )
{
	#won't work with vmail users, to avoid "spamd: handle_user (userdir) unable to find user:" message
        #xfilter "/usr/bin/spamc -u $USER" 
        xfilter "/usr/bin/spamc"
}
#Optional : if we want, detected spams could be moved to a specific folder :
#if ( /^X-Spam-Status: Yes/ )
#{
#       to "$HOME/Maildir/.SpamAssassin/"
#}

SpamAssassin

Installing

root@host:~# apt-get install spamassassin spamc

Create working folder and set rights

root@host:~# su - vmail/
vmail@host:~$ mkdir .spamassassin/
vmail@host:~$ chmod -R ugo+w .spamassassin/

Configuration

root@host:~# mkdir /var/log/spamassassin/; groupadd spamd; useradd -g spamd -s /bin/false -d /var/log/spamassassin spamd; chown spamd:spamd /var/log/spamassassin

/etc/spamassassin/local.cf

rewrite_header Subject *****SPAM*****
report_safe 0 

/etc/default/spamassassin

OPTIONS="--create-prefs --max-children 2 --username spamd -H /var/log/spamassassin/ -s /var/log/spamassassin/spamd.log"
CRON=1 
root@host:~# systemctl restart spamassassin

Train our SpamAssassin filter

/usr/local/sbin/spamassassin_learn.sh

#! /bin/bash

#Mails in Spam folder are Spams
sa-learn --no-sync --spam /var/vmail/mydomain.net/shebang.thedolphins/Maildir/.Spam/{cur,new}
#Mails in Nospam folder are legit emails
sa-learn --no-sync --ham /var/vmail/mydomain.net/shebang.thedolphins/Maildir/.Nospam/{cur,new}
#Once processed as spam we put mails in trash folder
for i in /var/vmail/mydomain.net/shebang.thedolphins/Maildir/.Spam/{cur,new}/*; do
        mv "$i" /var/vmail/mydomain.net/shebang.thedolphins/Maildir/.Trash/cur/
done
#Once processed as legit we put mails in INBOX
for i in /var/vmail/mydomain.net/shebang.thedolphins/Maildir/.Nospam/{cur,new}/*; do
        mv "$i" /var/vmail/mydomain.net/shebang.thedolphins/Maildir/new/
done

/etc/cron.d/spamassassin

*/15 *  * * *   root    /usr/local/sbin/spamassassin_learn.sh

Sources

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