Markdown is more of a data cleanliness concern, keeping your markup simple and parseable. But because email had WYSIWYG GUI clients dating back to the 90s, ther

Markdown is more of a data cleanliness concern, keeping your markup simple and parseable. But because email had WYSIWYG GUI clients dating back to the 90s, there's too much entrenched inertia to change it now. Adding Markdown parsing would be pointless because nobody composes emails in Markdown when they can just select text and make it bold, etc., right in the GUI.