Were is quotas information stored

[Denis BUCHER]

Hello everyone,

As it seems impossible to access users accounts of many domains in cyradm,
As it seems impossible to change the quota of a user in another domain,

I would like to know where is stored the quotas for a specific user
account ?

For example I have user dbucherml at mydomain3.com, with path :
/var/spool/imap/domain/m/mydomain3.com/d/user/dbucherml/

Where is the quota information stored, and how could I set unlimited
quotas ?

Thanks a lot for any help...