How to search for emails "on hold opt out" and not "on hold bounce"
You can perfectly get the result you want navigating to Search - Advanced Search and expand the Mailings section, from there you can search for bounced emails or opt-out request specifying a date range.  

If you cannot see the Mailings section navigate to Administer - Customize Data and Screens - Display Preferences and make sure you have Mailing ticked under Contact Search

You can do the same from Search - Search Builder selecting Contact as record type and On Hold or No Bulk emails(User Opt Out) as the field.

You can also bulk Unhold Emails from the action menu in the search result, selecting the contacts you think they shouldn't be on hold.

Hope that helps.