When you don’t want a contact to receive an email, you can put them on the Suppression List or the Blacklist.
You can upload a database which is already known as bounce or invalid email data from another platform or you know for sure that those IDs are not interested in any of your emails or bounce email address from any other source.
So you can upload such emails address in your Blacklist/Suppression list in advance so they won't receive your email even though if they represent in any of your email contact lists.
Those contacts status will be changed from confirmed to Blacklisted as soon as you will add or import any contact in your Blacklist/Suppression list.