mail size - mailbox quota

[Clemens Hermann]

Hi,

I am using qmail with virtual users.
Now I have two questions:

1. what is the best way to set a quota on the boxes? I would appreciate
it if there was a "centralized" way so that I would not be forced to put
a .quata file in any mailbox.

2. how can I set a maximum limit for incomming mails?

thanks

Clemens