Not a bug per se but a feature request.
Make MariaDB the default DBMS of iRedMail. Especially with the new Ubuntu LTS coming out next month (MariaDB will be on the main repos), I think it makes perfect sense ditching MySQL which most likely will become cloused source anyway.
Version 10 of MariaDB has a ton of performance improvemnts including a new innodb engine: you can check a comparions article here: http://sobstel.org/blog/mysql-like-data … omparison/