If you don't want to use PureMessage on the server side, you can set up Mozilla filter instead based on the ranking.
1. Create a New Filter
2. There is how the default filter rules page looks like
3. Use the drop down box for header (default is Subject) and choose Customize...
4.add X-PerlMx-Spam as a new message header
5. set whatever rules you want to mail that matches
30% possibility as junk would Gauge=XXX
50% would be Gauge=XXXXX
Viola, you are done.
You can find examples on how to do this if you other mail client. (don't forget try to annoy the "other" "enterprise blah blah blah calendar blah blah blah" client users with this super cool trick, it works from Mozilla Suite too, not just Thunderbird, also, just use about:config, don't even bother with user.js)