When users of Lavabit, an encrypted e-mail service, logged on to the site this past August, they found a bewildering letter on the site’s main page. Ladar Levison, the founder and sole employee of Lavabit, had shut down his business rather than “become complicit in crimes against the American people.” Lavabit subscribers would later discover that Levison had walked away because federal investigators had asked him to hand over his master decryption key, which would have granted them unfettered access to most of Lavabit’s data. Shortly afterward, the encryption provider Silent Circle followed suit, summarily deleting its users’ stored mail and mothballing its e-mail servers. In the wake of the Snowden revelations, which should have driven demand for their services, encrypted e-mail providers were, in the United States at least, rapidly becoming an endangered species. This leads to a question that has received relatively little attention: Why is encrypted e-mail so rare in the first place?