Just found this forum post[1] and YouTube video[2], it clearly explains how to add a third-party Roundcube plugin, "register"[3] (from http://myroundcube.com/) to allow self-registering new mail user accounts for SQL backends, work well with iRedMail-0.8.3 in production.

[1] Register plugin Driver for iRedmail: http://myroundcube-plugins.40634.n3.nab … 24584.html

[2] iRedmail Server – register plugin installation tutorial (postfix driver): http://www.youtube.com/watch?v=ozhFt5ILWr8

[3] Register plugin: http://myroundcube.com/myroundcube-plug … ter-plugin

Notes:

*) PostfixAdmin is not required.
*) This plugin should work with iRedMail for both MySQL and PostgreSQL backends.
*) There're many more Roundcube plugins available on myroundcube.com, includes a calendar plugin.

Hope it helps.