More control over mail quotas for accounts

I would like to see more granular control over mail spool quotas.

Either set up a maximum quota at the package level (so a lower priced plan has 50MB mail spools and a higher price plan has 100MB mail spools) and not allow users to modify this.

Or

A way to allow users to change the mail spool up to a certain limit. Example might be: 5 accounts max, and 100MB total for the account, and either one email account can use all 100MB or 2 accounts can use 50 each or one at 60 and one at 40 etc... Or all 5 accounts can use 20MB each...

Right now, customers can change their quota to anything they like (even unlimited) which is not ideal.

Original thread: http://forums.cpanel.net/f145/more-control-over-mail-quotas-accounts-247941.html