Rated 5 out of 5 stars
This is an extremely useful add-on, does exactly what the description says and does it well: you can specify the settings (in prefs.js, user.js, MCD or any other auto-deployment way) to inject passwords to Thunderbird/Firefox password manager. I was looking for something similar for 2 days, this add-on should be more visible.
A recommendation for the developer: remove the "experimental" property, it works perfectly in the latest (45.8.0) Thunderbird (didn't try it in Firefox). And maybe write a blog post about it, there's just no way to find it using public search engines.