dovecot - Apr 2008 - Delete old mails and refresh quota

Hello.

I use dovecot 1.0.13. So, I can't use expire plugin (require dovecot
1.1+).
For delete old mails in Junk mailboxe, I use a cron:
find /var/mail/vmails/ -regex '.*Junk/cur/.*' -ctime +30 -delete

It works.
However, quota is not refreshed. If my quota is to 90% and I delete 85%
of my mails, quota still 90%, not 5%. I must delete my maildirsize after
this cron.

Do you have another solution to actualisize my maildirsize after a
delete of mail?

Thanks!

 - Nicolas.