<p>Has anyone got a working solution without some Java/COM-bridge? E.g. process the Email as a file (.msg) rather than locating the data that is referenced in the Clipboard?</p>

I did make some headway on this sort of thing a few years back using
Apache POI
to extract the contents of an email from .msg files.  I'm pretty sure they have a simple swing explorer / viewer that you can use to examine the structure within the compound document format, but I can't find it right now.
I was able to extract most information that I was interested in but was ultimately wanting to create a mime format version of the message and couldn't extract all the information I needed in a format I could use.