Certain DLP policy response actions allow you to enable email notifications. Every 24 hours MVISION Cloud sends a maximum of 10,000 notification emails to your org to let you know about DLP policy incidents. Once you reach the maximum, you will not receive any notification emails until the 24 hours ends. Then you will again receive email notifications.
You can do any of the following to avoid this:
1. Edit DLP policy responses to disable user notifications for Quarantine or Delete response actions.
2. Enable Summary email notifications so each user receives a daily list of all their violations. Configure this via Policy > Policy Settings.
3. Remove the User Notification response from specific DLP policies.