What is Confirmed Opt-In Data?

A “confirmed (closed loop) opt-in” means that following an opt-in request, a confirmation email is subsequently sent to the person notifying him that some action is necessary before their email address will be added to the list which will be transferred to a third party for commercial use.  The person must respond or take other action to be considered “confirmed”.  This option is not required for CAN-SPAM compliance.