To put closure on this topic: I communicated with Freelists.org. To be
archived, a post must be either plain text or a multipart MIME message
that includes a plain-text/quoted-printable part in addition to HTML. If
your message is HTML-only, it will *not* be archived. There is no plan
to alter this behavior.
In short, use plain text. It's the easy, list-friendly way.
--
Carl Distefano