A blocked contact is a recipient who does not wish to receive any further emails from you. A contact can block themselves by clicking on an unsubscribe-link in your mailings, or they can be blocked manually by you. If a contact is blocked, no more mailings can be sent to that person. Even if the contact is in a contact list you use for a mailing, the blocked contact will be picked up automatically once you click send and omitted from the sending.
The blocked contact will now have a red stop-icon in front of the email address.
(Don’t see the red stop-icon? Update your browser!)
PLEASE NOTE! You shall not unblock a contact if the contact has unsubscribed themselves from your mailings. Only if the contact has given express consent to receive your mailings again is it ok to remove the block.