Rated 5 out of 5 stars
I can't believe the absurd policy taken by Mozilla regarding add-ons, punishing the developers with continous changes, being mandatory to rewrite the code of extensions. We use this extension since YEARS AGO. This feature MUST BE INCLUDED with Thunderbird. If you plan to screw up the developers, be assure to include the most used extensions, like you do with Lightning.
Please, update this extension, the "signature" option incuded with Mozilla don't work properly.