Does anybody know if I can use a Tyvek envelop to send a rather large number of pages to my pal? It's not made of paper, so I'm not sure if that's allowed.
(In case you're not familiar with Tyvek: it's a kind of tear free envelop from a polyethylene type of material).
I haven't tried, but I would say a cautious no to that. The reason being, plastic can be melted down into all kinds of other shapes etc.
I think you would be better off with a sturdy envelope, perhaps one with a card backing on one side, or sending the documents in multiple conventional envelopes.