The only safe email is text-only email
I've noticed that "if it's not plaintext, it gets deleted without being read" seems to be a pretty common rule among Germans on the Internet, who also have a tendency to like specifying very exactly what they want of email to them. Here's a few examples:https://www-user.tu-chemnitz.de/~heha/email.en.htmhttp://problemkaputt.de/email.htmhttps://www.gaertner.de/~neitzel/email-to-mn.htmlhttp://www.karo-electronics.de/448.html...and of course there's this:http://arc.pasp.de/