[pomatic]

I'm sure markdown email has been done? But just didn't gain traction?

[colonial]

GNOME Evolution supports Markdown natively (I believe either raw or rendered to HTML on send; I use the latter.)

[jaffa2]

Mailmate on macos solves this very nicely. As a bonus my html mails have never looked better and i get the bonus of writing in text using markdown . Currently evaluating it.

[Avamander]

There's no The Markdown that's standardised (or safe enough), that it could be implemented like that unfortunately.

[xigoi]

Thank you. I hate when people say “Markdown” as if it was a single language and not a collective term for 100+ kinda similar languages.

[DavideNL]

For macOS check MailMate : https://freron.com/