Why can I not contact a contact that has been archived?

Contacts are archived when they request to be unsubscribed. Archived contacts cannot be contacted again through Agent Legend. This is permanent and in place to maintain compliance with SPAM regulations. 

Your Archived Contact List should basically be treated as a Do-Not-Call list. 

Contacts can unsubscribe by clicking the button available at the bottom of the emails sent out OR by responding through SMS with "Stop" or "Take me off your list".