Today’s paper is very similar to
What Deters Jane from Preventing Identification and Tracking on the Web? and shares an author. The main difference is that it’s about email rather than the Web. The research question is the same: why don’t people use existing tools for enhancing the security and privacy of their online communications? (In this case, specifically tools for end-to-end encryption of email.) The answers are also closely related. As before, many people think no one would bother snooping on them because they aren’t important people. They may understand that their webmail provider reads their email in order to select ads to display next to it, but find this acceptable, and believe that the provider can be trusted not to do anything else with its knowledge. They may believe that the only people in a position to read their email are nation-state espionage agencies, and that trying to stop them is futile. All of these are broadly consistent with the results for the Web.
A key difference, though, is that users’ reported understanding of email-related security risks is often about a different category of threat that end-to-end encryption doesn’t help with: spam, viruses, and phishing. In fact, it may hurt: one of Gmail’s (former) engineers went on record with a detailed argument for why their ability to read all their users’ mail was essential to their ability to filter spam.  I’m not sure that isn’t just a case of not being able to see out of their local optimum, but it certainly does make the job simpler. Regardless, it seems to me that spam, viruses, and phishing are a much more visible and direct threat to the average email user’s personal security than any sort of surveillance. Choosing to use a service that’s very good at filtering, even at some cost in privacy, therefore strikes me as a savvy choice rather than an ignorant one. Put another way, I think a provider of end-to-end encrypted email needs to demonstrate that it can filter junk just as effectively if it wants to attract users away from existing services.
(In the current world, encryption is a signal of not being spam, but in a world where most messages were encrypted, spammers would start using encryption, and so would your PHB who keeps sending you virus-infected spreadsheets that you have to look at for your job.)
Another key difference is, you can unilaterally start using Tor, anti-tracking browser extensions, and so on, but you can’t unilaterally start encrypting your email. You can only send encrypted email to people who can receive encrypted email. Right now, that means there is a strong network effect against the use of encrypted email. There’s not a single word about this in the paper, and I find that a serious omission. It does specifically say that they avoided asking people about their experiences (if any) with PGP and similar software because they didn’t want to steer their thinking that way, but I think that was a mistake. It means they can’t distinguish what people think about email privacy in general, from what they think about end-to-end encryption tools that they may have tried, or at least heard of. There may be a substantial population of people who only looked into PGP just enough to discover that it’s only useful if the recipient also uses it, and don’t think of it anymore unless specifically prompted about it.