Today (2016 january 18) I install roundcube, it has excellent performance. What problem will come future I don't know. today I get problem in password changing, Only admin user can change password. General email user cannot change passwd. I using it with iRedmail. There is any solution for that problem ?
Checkout the password plugin that comes with Roundcube, it has drivers to work with most mail server backends. I'm not sure what iRedmail uses but chances are there is something that would work.