Rated 1 out of 5 stars

Frustratingly this addon works fine at what it does. However on many RSS feeds (eg allwallpapersfree) it will open your browser for all the "social" links. So yes, you get the web page in Thunderbird. You also get Firefox opening and loading 2 or 3 extra tabs.
Far, far worse than not having the addon (considering the purpose you get the addon is to avoid Firefox).

This review is for a previous version of the add-on (3.2.8.1). 

ThunderBrowse doesn't support popups so any site with them will most likely open said popups into Firefox. It's one thing I'm planning on working on.