Changing the application that opens link in Mozilla Thunderbird 2.0, as I recently discovered, is not trivial (at least not in Linux). I’m doing this using Mandriva 2007.1 Free, so other distributions may handle this differently.

Here’s what I had to do to get Thunderbird to open URL’s in Firefox.

1) Open Thunderbird, then go to the menu option Edit->Preferences. A window will open, now select the ‘Advanced’ option at top, and then click the ‘Config Editor’ button near the bottom.
2) search for the Preference Name called network.protocol-handler.app.http. On Mandriva this points to /usr/lib/thunderbird-2.0b2/open-browser-sh
3) If you open the file /usr/lib/thunderbird-2.0b2/open-browser.sh you will see its a shell script that checks gconf to see what browser should be used (I don’t know why they make this so difficult). There was a comment in the script that said the default browser was stored in the gconf key ‘/desktop/gnome/url-handlers/http/command’
4) To see what the current application being used is: gconftool -g /desktop/gnome/url-handlers/http/command
Now you are ready to set this key to use a new application, run the following command:
gconftool –type=string -s /desktop/gnome/url-handlers/http/command ‘/usr/bin/firefox “%s”‘

Thats all you should have to do, you don’t have to restart Thunderbird as the settings should take effect immediately. I hope that soon Thunderbird makes this much much easier.

*Note: One other option you might try doing is when you have opened up the Thunderbird Config window, you might be able to edit the value of network.protocol-handler.app.http and set it to the location of your preferred browser. I have not tried doing it this way so I can’t be sure if this would work, though I suspect it would.

The Thunderbird config window looks like this:
Thunderbird 2.0 Config window