What is an "aggregate" GB quota?

If a customer has purchased 20 GBs of storage for a given month, that becomes the customers aggregate quota.

The domain admin can then allocate that 20 GBs between mailboxes and other services in a way that maximizes the storage resources. The domain admin has the flexibility to allocate larger mailbox (MB) quotas to heavy users and smaller mailbox (MB) quotas to users who only send and receive emails occasionally. This saves you money.