Most interesting. As part of my periodic rotation of strong random passwords on my never-used-but-maintained-so-family-can-still-tag-me-in-things-only-they-care-about Facebook account, I noticed there's an option to Encrypt Notification Emails. I've enabled that, and assume that the tiny set of people I know who actually use PGP might be interested to know of this feature. All one of them follows me on here so, my duty is done!