Sieve Email Filtering with Dovecot and Roundcube

Sieve filtering is a very useful feature on your own email server as it lets you to define powerful filtering options for your email server. In this guide I will explain the steps I used to enable sieve filtering on my server.

I assume your (optionally multi-domain, debian based) email server is already configured with postfix, dovecot and roundcube and you would like to enable sieve filtering and manage those filters using roundcube’s managesieve plugin.

Install packages: apt-get install dovecot-sieve dovecot-managesieved
Edit /etc/dovecot/conf.d/90-sieve.conf
```
plugin {
  sieve = /var/vmail/%d/%n/sieve/dovecot.sieve
  sieve_dir = /var/vmail/%d/%n/sieve
}
```
sieve and sieve_dir variables are user specific. Here %d and %n are variables, explanation is in /usr/share/doc/dovecot-core/dovecot/wiki/Variables.txt.gz. You need to set these variables in accordance with your (multi-domain) installation.
Edit /etc/dovecot/conf.d/20-managesieve.conf, enable services below by uncommenting them.
```
service managesieve-login {
  ...
}
service managesieve {
  ...
}
```
Note that you should disallow access to port number 4190 using firewall rules. I recommend using ufw for simple iptables management.

Edit /etc/dovecot/conf.d/15-lda.conf

protocol lda {
  mail_plugins = $mail_plugins sieve
}

Edit /etc/roundcube/main.inc.php

$rcmail_config['plugins'] = array(
  'managesieve'
);

Edit /etc/roundcube/plugins/managesieve/config.inc.php

<?php
  $rcmail_config['managesieve_host'] = 'localhost';
?>

Restart services:
service dovecot restart
service apache2 restart
Login to roundcube and test filters. I created one that activates when email subject is equal to ‘test’ then moves it to another folder.

Happy administration!