"[Facebook] Encrypted notification emails are going away soon"

"Encrypted notification emails are going away on Dec 5th. Review your settings."

I'm assuming usage was literally hundredths of a percent if not less, but it was one of the first things I switched on back when I wanted to see how useful I could make PGP in my day to day life. Pretty sure I set up my keybase account around this time too.

Link is to the settings page where you can enable the feature with your PGP public key. The page now presents the deprecation notice up top.