I have a text file on disk containing a valid RFCnnnn email message. It has all of the headers, including From:, To:, References:, and Content-type: (it's a multipart/alternative). One alternative is quoted-printable text/plain, and the other is HTML.

Is there anything out there already that will let me look at this arbitrary file as if it were an email, without having to hook it into mailboxes/maildirs/indexers? Just extract that text/html section and render it with SHR, nothing about replying or forwarding. Or strip out the the quoted-printable escapes and refill the paragraphs. It seems like someone somewhere would have already written a package that sits on top of emacs-mime and does this.