Display markdown emails via markdown-mode

Hi all,

I have emails with Content-Type: text/markdown and I would like to view
such emails in markdown mode somehow. Currently, when I receive such
email, gnus/message-mode knows to identify the mime, but it displays the
email the same way it displays text/plain.

Ideally, I would like gnus/message-mode to process such emails the same
way it processes html: identify the Content-Type, and send it to
eww. For markdown, it would be through markdown-mode's live-preview,
which displays markdown buffers in eww. Worse case scenario, I can
convert markdown to html and open it via eww.

Context:

At work, there are many tools that generate all sorts of updates. I have
a process that collect these updates for me and store it as messages in
maildir format. I use markdown for the message Content-Type, and use
gnus to read these messages.