checking quota

[Patrice]

Hi,

I would like to implement the quota checking within my MTA which is exim 
and not use cyrus quota

what would be the less consuming way to do it ?

- check the quota.db  and extract the current mailboxe size for a 
particular user ?
- connect with tcp on imap and read the current quota value for the user ?

if the effective quota is > of a value defined into my ldap I deny the 
delivery to cyrus-imap

Thank you for you advices

Patrice