I can see your predicament. 'Out of the box' silktest doesn't recognize the items inside the windows of outlook. I have the same problem with many other application where silktest can see the main windows but does not see any items within them.
1. Add the following executable to the Extensions Enabler: msimn.exe
2. Enable IE4 OCX as the primary extension for this executable
3. Do the same in the Options/Extensions for this executable
4. You may check the Java checkbox in the extensions if you need it.
5. Make sure that you don't use the DOM extension.
6. Also, it may interfere with plain browser testing.
Note that this procedure works for any application that includes the IE browser component (IE 4 or IE 5).