In an otherwise unmodified Plesk installation, default service plans restrict a subscription to a maximum of 100 mailboxes. With Plesk Premium Email, each such mailbox would incur licenses costs, and an individual subscription being allowed to create up to 100 mailboxes may cause the provider to no longer be in compliance with the Plesk Premium Email license limitations.
A couple of means exist to control licensing overruns better;
- Reduce the number of mailboxes per subscription without allowing overrun (not recommended),
- Reduce the number of mailboxes per subscription, allowing overrun and enable alerting (recommended).