Rated 4 out of 5 stars

Very good addon. Focus on which account you are using. (color in folder list makes it easier to identify accounts).
Have an issue with it as (on Thunderbird/Shredder 3.3a4 on windows) the status bar text disappears. Hovering a link on a email does not show the result in the status bar (also folder info from the Nostalgy addon does not show).
From the review of HekMek, (where he mentions no text on hovering buttons) this might not be just due to Shredder.

Good work nonetheless

This review is for a previous version of the add-on (3.3).