A system that determines if mail contains life-harming materials before the mail enters the interior of a receptacle, i.e., mail box. This invention accomplishes the foregoing by issuing stamps that uniquely identify the stamp and identify the mailer to whom the stamp was issued; having a scanner at a receptacle read the stamp and send the unique identifying code contained in the stamp to a data center that checks if the stamp is genuine; and stores the stamps unique code before mail is permitted to enter the interior of the receptacle.