Change default directory structure

Hi,

iredmail 0.2.2 open
MySQL
Ubuntu 12.04

I would like to change the default directory structure eg: /home/vmail1/u/s/e/user-2013.09.03

to

/home/vmail1/user-2013.09.03

I found this topic but it seems it is not working:

http://www.iredmail.org/forum/topic947- … users.html

Where can I change the creation of directories?

Thanks, Robert