If routine surveillance looks for "buzzwords" wouldn't it also look for "unusually encrypted" mail, and divert it to the CRAY code breakers? And wouldn't strong encryption weaken your claim of "innocent content" by implying a deliberte attempt to conceal?

Obviously you should print it all out, take it to a post office remote from your home, and mail it - disguised as an advertisement from a "book of the month club" - to a PO Box that your friend rents for one time use under an assumed name. The receiving PO Box of course should be at least two towns away from where your friend lives.

The only stuff my postal service doesn't look at is "junk mail," and email is all "open to the public" regardless of how it's sent.

John