[Dovecot] Question about directory hashing

[Javier de Miguel Rodrí­guez]

Hello

     I have been reading http://wiki.dovecot.org/MailLocation and 
http://wiki.dovecot.org/Variables and I do not fully understand the 
directory hashing feature. I want to migrate > 70.000 users from Sun 
Messaging to Dovecot using imapsync. I have tested with 
mail_location=maildir:/buzones/us.es/%1Hu/%2.1u/%n but I get the 
following directory tree:

`-- 0
     |-- -
     |-- 1
     |-- 2
     |-- 3
     |-- 8
     |-- _
     |-- a
     |-- ab
     |-- b
     |-- c
     |-- d
     |-- e
     |-- ev
     |-- f
     |-- g
     |-- h
     |-- i
     |-- ie
     |-- is
     |-- j
     |-- jb
     |-- jj
     |-- jp
     |-- js
     |-- k
     |-- l
     |-- m
     |-- mb
     |-- n
     |-- o
     |-- p
     |-- pp
     |-- q
     |-- r
     |-- rm
     |-- s
     |-- t
     |-- u
     |-- v
     |-- w
     |-- x
     |-- y
     `-- z

     The ideal directory layout should be the following:

     First directory level: Letters from a to z
     Second directory level: Numbers from 0 to 200
     Third directory level: %n (username without @domain)

     How can I achive this directory layout (or other optimized for 
70.000 users) . I use ext3 on Red Hat Enterprise Linux 5 with directory 
indexes on.

     Regards

     Javier de Miguel