The Server checks the Account storage quota for every connected user. If the Account storage is limited, and the specified percent of that limit is already used, the Server generates an alert message for that user.
The Account settings specify when the Storage Quota Alerts should be generated.
After a Storage Quota Alert is sent to the Account user, the Server does not generate Storage Quota Alerts for that Account for 10 minutes.
Note: if a user connects to his/her Account using the POP module, the Storage Quota Alert is displayed as an error message, and the user should try to connect again. If the user does not retry immediately, but makes the next connection attempt more than 10 minutes later, and the Account is still over its storage quota, the Storage Quota Alert is generated again and the connection is refused again. Instruct your POP3 users to retry immediately if they see the Storage Quota Alert messages.