Not stop directly, but provide a definite link back to the sender if anything bad happens, be it a terrorist attack, accidental aircraft fire because of non-declared hazmat, or just spillage or damage.? If someone is sending something by mail/parcel they are clearly trying to avoid being caught, as opposed to a suicide bomber.
Ted Kazcynski mailed his bombs in packages covered in stamps and dropped off in the blue boxes.? That's why you can't send anything more than 12 ounces except in person or with electronic (traceable) postage.
Kurt Laughlin
