What is a Global Suppression List?
The Global Suppression List is basically a ‘do not send’ list. It prevents any other messages from being sent to that address.
Any subscriber that specifically requests to be removed from any further communications will be added to this list. (This would be following a complaint, not just following an regular ‘unsubscribe‘ situation)
Any email address that bounces back because it is invalid would also be added to this list.