Ok, yes in some countries this is absolutely true, while in many others it is not - or if it is, it is overlooked completely. I certainly understand your predicament.
It may be overlooked usually, but I am certain some agencies have your P.O. box or what ever and they will try to intercept it. And I know they will not do it, but they may look for fingerprints. I am kind of paranoid, sorry.

Once I get the bitcoin address, I will post it to this thread, so there really is no reason for you to go and purchase a subscription to Protonmail, unless you wanted it for other reasons. Just saying ...
I would be more acceptable to a one time bitcoin address that was sent to me in private. Once I manage to buy those bitcoins (the dealer postponed the exchange so I am looking at other ways) it would not make a difference.

Thank you for your patience.