Ducksterman is correct! Getting a free boxes delivered to your house by the postal service and then turning them inside out to avoid the priority postage will cost someone. If it isn't mailed over the counter and caught by the postal clerk, it could be caught at the receiving end an the recipient will have to pay the postage due. If the recipient refuses to pay the postage due it is returned to sender and the sender is on the hook for the total round trip, that is, if he wants what he mailed back.
By the way, Consumer Reports recently did a comparison.
http://www.consumerreports.org/cro/m...stal%20service