Minimal password length is not working

==== Required information ====
- iRedMail version: 0.8.3
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Linux/BSD distribution name and version: CentOS 6.3
- Related log if you're reporting an issue:
====

Hi,

I've tried to specify 6 at Minimal password length and 20 for Maximal password length, but I can enter a password with only 1 letter.