About 35 years ago, my father did a bunch of social science research
consulting for CBS. For one of their studies, they sent people
port-a-punch cards, and had people just put a stamp on them to mail them!
I don't know what madhine they used (and my father has been dead
too long to ask him), but the IBM CEs were able to open the gate
wide enough to take cards with stamps on them, that had gone
through the mail!
I was very surprised. I had suggested using oversized cards,
and cutting off the end with the stamp.
--
Grumpy Ol' Fred cisin at
xenosoft.com