==== Required information ====
- iRedMail version (check /etc/iredmail-release): 0.9.2
- Linux/BSD distribution name and version: Debian
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx):
- Manage mail accounts with iRedAdmin-Pro?
- Related log if you're reporting an issue:
====

I closed this topic to early. Two important notes if you change password restrictions:

1.) the path for debain is /opt/www/iredadmin/settings.py and not /usr/share/apache2/iredadmin/settings.py like mentioned in wiki

2.) after changes to settings.py you need to restart webserver: service apache2 restart (I was surprised, different from PHP...) -> sorry, this is mentioned in your wiki - I didn't read carefully.