International Large Envelope/Flat

[ztams]

I understand that I can no longer ship merchandise internationally using the First Class Large Envelope/Flat rate as that is now solely used for documents.  My question is am I still allowed to use the large flat envelope to ship items as long as I pay the package shipping rate, or do I actually have to ship items in a box (package)?

[partial*eclipse]

Put a couple sheets of cardboard in, to make it rigid, so that it definitely is categorized a a package rather than as a flat.