USPS Priortity mail boxes reusable?

According to this, it's illegal

http://consumerist.com/2008/05/dont-reuse-that-usps-priority-box-its-illegal.html

http://www.thedenverchannel.com/news/16072154/detail.html

I have taken them apart, turned them inside out

Recently I tried to look for a box to "turn inside out", and THEY ARE MARKED ON THE INSIDE OF THE BOX!!!!

(How's that for being "green?"