The USPS Free Boxes Program: The Cheapest Way to Ship?
Military Care Package Kit | USPS.com
Are USPS Boxes Free? Here's How You Get Free Packaging
Free: USPS Priority Mail Box Size Guide - Stamps.com Blog
Sending Care Packages Made Easy: How to Score Free USPS Boxes < LDR Magazine
Covering up a free Priority box with a poly bag (and lesser postage), 'cause you think you're slick? Hope your customer appreciates the “Postage Due.” : r/USPS