Edit File: managesieve.xml
<?xml version="1.0" encoding="utf-8"?> <service> <short>ManageSieve</short> <description>The ManageSieve Protocol allows a local client to manage eMail sieve scripts on a remote server. If you plan to provide a ManageSieve service (e.g. with dovecot pigeonhole), enable this option.</description> <port protocol="tcp" port="4190"/> </service>