I've bashed and banged mhonarc, until it wrote out valid XML ;-)
You can view the results under
The thing is not perfect, for example if there are non-Unicode
characters in the email, then the XML parser will throw an exception and
quit. Perhaps someone knows how I can suppress such characters, in my
case it was a ^P character. The mail itself was labelled as text/plain,
so mhonarc passed its contents through unchanged.
DENIC eG, Systementwicklung