The point I was trying to make was that if we simply filter *ALL* messages
that aren't text/plain, we're sending a message that we've given up on
multipart/signed messages as well.
More generally, the issue is that MIME is used for lots of things besides
"fancy markup format du jour", and if we require that all messages be
text/plain we end up banning things like signed text/plain messages, nested
RFC822 messages containing text/plain parts, messages consisting of
multiple text/plain parts, and so on. And there are perfectly legitimate
reasons to post these sorts of things to lists.
Heck, we even end up excluding Internet-Draft and RFC announcments, which use
multipart/mixed, multipart/alternative, and message/external-body to give
readers a convenient way to access the actual document. (It also is a
mechanism I happen to use regularly, and I would hate to lost it.)
Surely after almost a decade of MIME experience, we can do better than just
saying "Throw out all stuff that isn't text/plain".
Exactly. Much better rules are possible, and in fact much better rules are in
wide use on other lists.
Ned