Email encryption has been around for decades but it’s still very rarely used. If the Pakistan secret services see people using encryption software then they go and torture them as they must have something to hide even if that’s something as innocent (in the west) as converting to Christianity. Phil Zimmermann answers the eternal question perfectly here:
If you really are a law-abiding citizen with nothing to hide, then why don’t you always send your paper mail on postcards? … no one draws suspicion by asserting their privacy with an envelope. There’s safety in numbers. Analogously, it would be nice if everyone routinely used encryption for all their email, innocent or not, so that no one drew suspicion by asserting their email privacy with encryption. Think of it as a form of solidarity.
Link: Why I Wrote PGP