Selects the hard bouncers from the _Bounce data view. Requirements:
SELECT b.SubscriberKey, b.EventDate AS BounceDate
From _Bounce as b
Inner join _Subscribers as s on s.SubscriberID=b.SubscriberID
where b.IsUnique=1
and DateDiff(day, b.EventDate,GetDate()) = 4
and s.status = 'held'