NoWEBSearch for Mozilla Thunderbird
The addon disables the web search like bing, google, yahoo etc. If you are annoyed from these kind of searches ... this is for you.
The addon does not mess with Thunderbird configuration in any way. It simply hides the web search when you start typing.
The solution was taken from : http://forums.mozillazine.org/viewtopic.php?f=39&t=2420963
download the .xpi file. Open Thunderbird Addon Manager and add addon from file. That's it.