I just uploaded Empty ‘em version 0.781 to addons.mozilla.org. The add-on now supports Thunderbird version 3.3a4pre. You can alternatively get it from GitHub downloads:

https://github.com/downloads/asolkar/emptyem/emptyem-0.781.xpi

It should appear on AMO listing shortly.

I will not be working on the add-on at least for a month, since I am traveling.