Suppressed emails allow you to specify email addresses that you never want to send emails to. The email address that you specify supports wildcard. This can be used to manage people who have previously flagged one of your campaign as SPAM. Our system actually automatically populate this list for you when someone flags one of your campaign sent through our system as SPAM.
Specific email address: localpart@domain
Any email addresses at one domain: @domain
A specific local part at any domains: localpart@