The problem with that is it's simply not practical to expect all of your contacts – to say nothing of your grandparents – to do the same, which means that at least some of your emails are going to be exchanged in the clear. And as this fascinating Bloomberg report about the surveillance activities of the former Tunisian regime reveals, that creates another kind of vulnerability that concerns not only what you send, but also what you receive:

Asma Hedi Nairi, a former Amnesty International youth coordinator, says e-mails she and her friends exchanged were replaced by messages ranging from random symbols to ads for rental cars. Opponents of the regime toppled in January’s revolution received threatening messages such as “you can run but you can’t hide,” while people with no role in politics found their correspondence snagged if it inadvertently included words flagged as critical of the government. Ammar 404 even damaged reputations by inserting pornographic images in work e- mails and routing intimate photos onto Facebook, Nairi, 23, says.

What makes this story particularly disturbing is that practically all the technology used to carry out this disinformation campaign in Tunisia was provided by Western companies, who seemed to view it as a test run:

Western suppliers used the country as a testing ground. Moez Chakchouk, the post-revolution head of the Tunisian Internet Agency, says he’s discovered that the monitoring industry gave discounts to the government-controlled agency, known by its French acronym ATI, to gain access.

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