[vchkpw] Quota problem

[zafar]

hello all
    i am facing problem in assigning quota through vqadmin.
The Quota is successfully assign to user but user can still receive mail
with high capacity and mail not bounce back to user.
so how can i manage that problem ,when a user mailbox quota is full then his
mail will be bounce back .
The one thing more plz tell me either quota which i allot it only applied to
maildir only or all folder which user create and also include
trash,sent,draft.
So plz guide me in this problem
thanks