[Exim] quota

Welcome


I just installed vm-pop3d and configured exim to delivery e-mails into "virtual directory".
I have a couple domains

the accounts has into /etc/virtual/<domain>/passwd
mail into: /var/spool/virtual/<domain>/<username>

all domains have specify into /etc/virtual/domains
:)

What I can set quota for this virtual user?
Is any posibly group quota? (per domain)?
If YES, so how I can do it?

Greetings
W.S.