Install | Topics | Beyond Lino

Full mail server

Dovecot

Install the Debian packages:

# apt install dovecot-pop3d  # optional
# apt install dovecot-imapd  # optional

Create a file /etc/dovecot/local.conf and add the following content:

listen = *, ::

auth_mechanisms = plain login

mail_driver = maildir
mail_path = ~/Maildir
mail_inbox_path = ~/Maildir/.INBOX

ssl_server_cert_file = /etc/letsencrypt/live/mail.mydomain.org/fullchain.pem
ssl_server_key_file = /etc/letsencrypt/live/mail.mydomain.org/privkey.pem

IMPORTANT: Mail location parameters should be in sync. Above means that the postfix config parameter is home_mailbox = Maildir/.

Control the Dovecot service:

# systemctl restart dovecot

Using hints from:

• https://tecadmin.net/install-dovecot-on-debian-10/

Spamassassin

Here we describe how to install Spamassassin to a Debian mail server with postfix and dovecot. Necessary packages are:

$ sudo apt-get install spamassassin spamc

We set up user account and group for spamd service:

$ sudo groupadd spamd
$ sudo useradd -g spamd -s /bin/false -d /var/log/spamassassin spamd
$ sudo mkdir /var/log/spamassassin
$ sudo chown spamd:spamd /var/log/spamassassin

Edit /etc/default/spamassassin to add options:

# Change to one to enable spamd
ENABLED=1
SAHOME="/var/log/spamassassin/"
# Options
OPTIONS="--create-prefs --max-children 5 --helper-home-dir  \
--username spamd -H ${SAHOME} -s ${SAHOME}spamd.log"
# Cronjob
CRON=1

Start spamassassin daemon and check corresponding processes:

$ sudo service spamassassin start
$ sudo systemctl status spamassassin
$ ps aux | grep spam

Further, we need to configure postfix master.cf to use spamassassin service:

spamassassin unix -     n       n       -       -       pipe
    user=spamd argv=/usr/bin/spamc -f -e
    /usr/sbin/sendmail -oi -f ${sender} ${recipient}

To mark spam messages, we configure /etc/spamassassin/local.cf

# rewrite_header Subject *****SPAM*****
rewrite_header Subject [***** SPAM _SCORE_ *****]
# Set the threshold at which a message is considered spam (default: 5.0)
required_score 4.0

After restarting spamd check the logs with

tail -f /var/log/spamassassin/spamd.log

For dovecot we need sieve-plugin

$ sudo apt-get install dovecot-sieve dovecot-managesieved

and edit /etc/dovecot/conf.d/20-lmtp.conf

protocol lmtp {
  mail_plugins = $mail_plugins sieve
}

After that restart dovecot.

To set up sieve filtering create default.sieve in /var/lib/dovecot/sieve/

require ["fileinto", "mailbox"];
if header :contains "X-Spam-Flag" "YES" {
        fileinto :create "Spam";
}

and compile this in /var/lib/dovecot

$ sudo sievec sieve/
$ sudo chown -R dovecot:dovecot sieve/*
$ sudo chmod a+x .
$ sudo service dovecot restart