What is overselling?
When you set resource limits for a reseller and enable overselling, a reseller can create accounts with resource limits that exceed the maximum amount that you allocate. After the total combined resources that all of the accounts use exceeds the reseller’s resource limit, the reseller cannot create new accounts. However, their accounts can continue to use resources, up to their own allocated resource level. The resource limit does not affect an account’s use of resources, only the reseller’s ability to create more accounts.
For example, you allocate 500 MB to the reseller Adam and enable overselling. Adam sets disk space quotas of 200 MB for four users. Combined, the users’ accounts can use up to 800 MB of disk space. However, after the accounts collectively use 500MB of disk space, they can still function, but Adam cannot create any new accounts.