Dovecot, Sieve & ISPConfig 3.1 with Roundcubemail and Thunderbird on Ubuntu 18.04


The ISPConfig3 Plugins for Roundcube connects to the ISPConfig remote API to add filters and does not use the the Dovecot Managesieve extension. Therefore the ISPConfig sieve rules are not overwritten like Thunderbird is doing.


Mozilla Thunderbird needs the sieve service installed to run.

Install the sieve daemon

apt install dovecot-managesieved

Enable ManageSieved on port 4190/tcp

vi /etc/dovecot/dovecot.conf
protocols = imap pop3 sieve
service dovecot restart

Check configuration

netstat -putan | grep 4190
tcp        0      0  *               LISTEN      5464/dovecot
tcp6       0      0 :::4190                 :::*                    LISTEN      5464/dovecot

Sieve rules are located in


The active sieve rule is usually a symlink to ispconfig.sieve

.sieve -> sieve/ispconfig.sieve

Open firewall

ufw allow 4190/tcp

Install Thunderbird Sieve Add-on

Enable sieve filter for IMAP account