If you have a Mac, and on occasion want to forward an email including all of the headers (such as, say, when reporting spam), you may have noticed that starting with a few iterations of OS X back, you could no longer easily populate a forwarding or replying email with the full headers of said email.
Back in 2014 Facebook announced that it was discontinuing the Facebook email service (where people could email you at email@example.com). That’s because it wasn’t very popular. But just in case you were one of the handful of people who used your @facebook.com email address, they kept a forwarding service on so that your Facebook email address would still forward to your address of record at Facebook. However, now Facebook has finally completely shut down the email service, including email forwarding.