(BTW, the search engine on the mhonarc list on mail-archive.com is
currently down, so I tried to search the archive before asking this!)
I upgraded mail-archive.com today, and it took a several hours for the
new search engine to re-index everything. Anyway, things are back up
and running; you might even notice slight improvements in performance
when searching.
Also, for what it is worth, the HTML 4.0 specification (www.w3.org)
has a tag for "include this bit of HTML from a file right in here" I
forget the tag name. The upside is it's exactly what you want; the
downside is I don't know of any browser that implements it. Perhaps
it's a good choice if you want to be, ahem, ahead of the curve.
Jeff