Sieve Plugins for Roundcube
In addition to the managesieve plugin that is included with Roundcube, there is also SieveRules plugin.
Copy the sample config file:
cp config.inc.php.dist config.inc.php
Then edit it to change some defaults to match our Sieve install:
$rcmail_config['managesieve_port'] = 4190;
To enable a Dovecot plugin like this one, add it's name to the $rcmail_config['plugins'] array in
$rcmail_config['plugins'] = array('managesieve');