Thunderbird, link handling preferences

Open links in firefox

Edit your pref.js file in .thunderbird/*default*/pref.js and add the following

user_pref("network.protocol-handler.app.ftp", "/usr/local/bin/firefox");
user_pref("network.protocol-handler.app.http", "/usr/local/bin/firefox");
user_pref("network.protocol-handler.app.https", "/usr/local/bin/firefox");

Open links in konqueror

user_pref("network.protocol-handler.app.ftp", "/usr/local/bin/konqueror");
user_pref("network.protocol-handler.app.http", "/usr/local/bin/konqueror");
user_pref("network.protocol-handler.app.https", "/usr/local/bin/konqueror");