There are a number of US laws that protect mail / post explicitly, and don't explicitly protect email. See this article on the matter: http://www.slate.com/ar

There are a number of US laws that protect mail / post explicitly, and don't explicitly protect email. See this article on the matter: http://www.slate.com/articles/technology/data_mine_1/2013/06/nsa_surveillance_why_the_post_office_doesn_t_spy_on_your_mail_the_way_nsa.html http://www.slate.com/articles/technology/data_mine_1/2013/06... One of the laws in question: http://codes.lp.findlaw.com/uscode/18/I/83/1708 http://codes.lp.findlaw.com/uscode/18/I/83/1708