[Dovecot] dict quota and quota recalculation

[Alex]

Hi
I am trying to migrate my courier server to dovecot and I've run into 
some problems.
One of the motive that I chose to migrate is quota reporting mechanism 
which in courier is a pain (if you need to display an accurate quota 
usage in the control panel). So I follow the instructions on migrations 
, I convert all the mailboxes, and the next step was to populate the 
quota table (I use quota/dict).

The quota table is empty. From the console (as root):
#echo "x GETQUOTAROOT Inbox" | USER=test at domain.net 
/usr/local/sbin/dovecot --exec-mail imap

- the result is :
| email          | used_quota | messages |
+----------------+------------+----------+
| test at domain.net |          0 |        0 |

 From mailling logs , relevant parts :

dict quota: user=test at domain.net, uri=proxy::quotadict, noenforcing=0
Namespace: type=private, prefix=, sep=., inbox=yes, hidden=no, list=yes, 
subscriptions=yes
maildir: data=~
maildir++: root=/root, index=, control=, inbox=/root
Namespace : Using permissions from /root: mode=0750 gid=-1

- and in the root folder I can see all dovecot specific files (dovecot*)

So basically if I execute the script as root the maildir is root the 
uid/gid is root
I search and I found a trick for home :

HOME=/home/sites/domain.net/mail/test/Maildir/; USER=test at domain.net; 
echo "1 getquotaroot inbox" | /usr/local/sbin/dovecot -c 
/usr/local/etc/dovecot.conf --exec-mail imap

(but first I must put used_quota and messages values on -1 in the quota 
table)

If I run this , all dovecot files are created in the user homedir 
(correct) but with the wrong uid/gid (root).
If I change the owner of that files , next time I run the same command , 
nothing changes (uid/gid remain vmail.vmail).

My questions are :
- is there a way to avoid this behavior (the owner of the dovecot files 
after quota recreation)?
- is there a better way to force all users quota recalculation?

PS: and yes , I need to know all quotas  even if the user haven't yet login