This works. Let that be clear.In the options, the Smaller and Larger buttons don't do anything. I'm not sure what they are supposed to do, but I don't see anything changing when I click them, so there's that. Secondly, the progressbar in the statusbar constantly animates, which is distracting. Should be disabled. Windows 7 x64, Thunderbird 24.2.0
/edit @Developer: perhaps you can use the progressbar that's also on the Quota tab on the dialog you get when going Inbox->Properties. It looks different (purple in my case) and doesn't animate.
/edit2 @Mozilla: don't remove newlines from my review please.
This review is for a previous version of the add-on (0.3.7).