I thought this little rubber stamp on the cover was interesting. from my google search, part 262 of the Postal Codes deals with records management??

I acquired several covers with this stamp, included in a lot of material for my other collection (Irish Hospital Sweepstakes tickets), which were illegal to ship into the US. What I don't understand is that apparently, the recipient DID in fact receive these envelopes, and from what I can put together from the materials, he did receive the ticket receipts that were included. I guess that the receipts are not illegal, but couldn't that be evidence to prove participation in illegal activity?