The right to freedom from search is not about envelopes. Arguments about cleartext online email cannot stem from paper equivalents - it must be about intent, how it affects our lives, not some rule-lawyering view.

Further, when govt attempts to prevent citizens from putting email into secure envelopes then its clear what's going on. Its goes from "I can easily read your email; thus its not protected" to "You must submit all you email for inspection!" That's clearly the sort of thing the 4th amendment is intended to protect from.