Hello,
Is there a way to get a RSS or email notification when a new notable suppression is created or enabled in ES?
You can create an alert and send an email for the following:
index=_internal sourcetype=notable_event_suppression:rest_handler "SuppressionAudit" action=create.
I know this is an old question, but have been doing some research lately myself and came upon this :). It only seems to apply when creating a suppression from ES either through Incident Review workflow action or through Notable Event Suppression page under Content Management --> Incident Review (I believe - working from memory presently).
You can create an alert to periodically run that monitors for new suppression. That would be the fastest way.