Event log filter Test exceeded the configured threshold (3 entries / 300 second(s)). 3 events (out of a total of 8) were dropped by this filter. You can review the dropped events in the event log (if the size of the event log is big enough).
This event is logged by EventSentry because a events matching a threshold filter (e.g. "Test") exceeded the configured limit.
EventSentry includes a threshold filter option with filters that allows you not only to control which events, but also how many events will be processed feature (e.g. only 5 per hour).
This feature can be configured at "Packages -> Filter Packages -> Package Name -> Filter Name -> Threshold".