[tbe]

That would be nice if it was standard for clients to display text/markdown rendered as styled text. This would require an actual standard for the markdown syntax though. Without the rendering, markdown is just text/plain.

Are there any mail clients that will send both the markdown source and the rendered HTML as a multi-part message?

[jwilk]

You can specify Markdown variant in Content-Type.

Source:

https://tools.ietf.org/html/rfc7763

https://www.iana.org/assignments/markdown-variants/markdown-...

[tbe]

Ok, good to know, thanks. The point still stands that the receiver's client probably doesn't bother styling the message. I mean even if GMail, say, was persuaded to do it, Outlook for instance wouldn't.