All mail in ballots, by law, have to be mailed out.
All mail in ballots are printed, folded, and stuffed in an envelope at the printers.
Also each printer encrypts it's own unique code on all ballots.
Companies that print ballots are specialized.
So, if a mIl in ballot is requested or mass mailed out, they should all have a printers code and folding kinematic artifacts resulting from folding print on paper.
Ballots not having those were not legally printed and folded by machine bby the official printer.