Re: Rmail-mbox branch

[Richard M. Stallman]

    I understand the question as "can we achieve interoperability with
    other MUAs, yet avoid (MIME-)decoding a message every time we present
    it?"  The answer is "only if you're willing to destroy information"
    for all MIME types except 'text/plain; charset=us-ascii'.

How do you reach that conclusion for text/html?

      The first two RFCs establish the requirement
    that mail shall be transmitted as plain ASCII text.[1]  The rest
    provide various conventions for how to serialize quite arbitrary
    objects, from non-ASCII text to video clips to binary blobs, as plain
    ASCII text.

HTML is made of plain ASCII text.