The reality is that all email servers are not created equal and complete confirmation of deliverability is not possible with some domains which give us the Catch All and Unknown results. What we can do is verify the status of each email address to help you decide how to manage your list. Consider these points in evaluating the risks involved in sending to Unknown or Catch All emails.
How were the emails collected?
If they are all opt-in emails from people who signed up for your communications then they are likely to be good addresses. If the list was purchased or inherited from another source then the performance of Catch All or Unknown emails are likely going to be weak and your sender reputation may suffer.
How old is the contact?
Most Catch All addresses are business domains. They are people’s work emails. If someone gave you their work email 4 years ago, they may no longer be employed there. The email won’t be opened or read by anyone. Even worse, it could bounce if the email address no longer exists.
If you’re confident in the way the contacts were collected, and the age of the data is relatively new then you may consider mailing to the Unknown and Catch All results. Just be aware that these emails may not match the performance of the emails verified as Valid.