I know that if you go in the mail and send a package in the way of priority shipping, come with a box in which the item free of charge for a supply ship. I want to print shipping labels online, as the cost much cheaper, but that means I can not get my free packing materials, even if I take the job? Ideally, I would be able to print postage, take my article in the mail, the request is a priority shipping box, package it, then bought my pre-shipping label on the box, they erbringen. Ist this possible?