Pre-set Mail Quota Limit

Hi..i'm a new user of the Cpanel. I'm trying to figure out how to pre-set each e-mail box has a fixed quota limit. For example, I've created a domain, and of course the domain user will create e-mail box for users, I want it to be 100MB each maximum, and the domain owner cannot change the e-mail box bigger then 100MB each. How do I do that? I look thru the Cpanel, I don't see anywhere can make such setting.
If anyone knows, please kindly let me know as well.

Thanks a lot.