"Requires additional items'
I have installed version 0.8 from official Mozilla repo ( and then I've tried 0.9 with the same effect ). Thunderbird 3.1.2 on Windows XP here.
The problem: extension does not seem to work and when I go to Thunderbird menu->Tools->Add Ons, I can see
Provider for Microsoft Exchange 0.9
Allows bidirectional access to Microsoft Exchange
Requires additional items
and the 'Options' and 'Enable' buttons are greyed out. I can only 'Uninstall' it.