maildir + quota

[Murat Arslan]

Hi all,

I use vchkpw-3.4.5 and imap-4.5.vchkpw, with maildir. I added 
3000000 (3mb) into the control/databytes file. But I want more.

How can I put quota on the system that calculates the sizes of the
folders of the user, and if quota exceeded how can I force
qmail to reject the incoming mail ?

Any help will be appreciated,
-- 
Regards,
Murat Arslan