hello
this is by default in email notification response rule (at least in DLP last versions) where you can set limit of email notification per day. If you need something more tricky you will have to define different response rule with some condition and then updating on regular basis list of people who already received notification.
Just take into account that only people who will be caught by this DLP policy will receive this notification, so it is not as a global notification to a population under control.
Regards