The soft bounce threshold controls the number of times an email is allowed to bounce before being unsubscribed, and it's set under User menu > Settings > Email > Suppression settings.
Soft bouncing can be a temporary issue (for instance, when a full mailbox gets cleared down), and sending to these email addresses later on may well succeed.
Using the Soft bounces report
The report lists all the contacts who've soft-bounced.
Any subsequently deleted contacts in the report will be denoted as 'Deleted contact' (apart from deleted suppressed contacts whose email addresses will need to be retained).
Filter by type
You can filter the list to exclude either 'soft bounces' or 'mail blocked' types.