Blocked people in the Marketo Engage database are marked blocklisted, unsubscribed, marketing suspended, and/or have an invalid or empty email.
In your Smart Campaign, click Schedule. Under Smart List Status, click the second link.
People who have reached their communication limits may also be blocked from receiving mails. Learn how to edit communication limits in the Admin section.
The Blocked People tab shows people who might not receive mailings.
Operational emails will be sent to people marked unsubscribed and marketing suspended.
There you go! Now you can be aware of who might not be receiving the mailings.