How are unsubscribes recorded? Where do they go?

When someone unsubscribes from your list they can choose to be unsubscribed from the current list they are on, or choose to be added to your unsubscribe list. When a recipient chooses to be removed from a single list, they are marked as unsubscribed on that list. If they choose to unsubscribe from all your lists, they are added to your unsubscribe list. Once a record is added to your unsubscribe list, they will no longer receive messages from any of your lists.