"Overriding Your Linux OS's default Mail Client" This is all easy GUI stuff: I've been using the typical Gnome default mail client, Evolution, on my Fedora iBook, but I use Thunderbird on my Ubuntu laptop mainly because I knew Thunderbird from having used it on Mac. Since Ubuntu comes with Evolution installed as its default, after you install Thunderbird from the repository, you must then tell the system that instead of using Evolution, you'd like to use Thunderbird for all those mailto: links and things like that. This is easily done by going to System > Preferences > Preferred Applications In the Preferred Applications window, simply select Thunderbird from the drop-down menu under the "Mail Reader" section. Click OK, and you're done. Should work like a charm. To do this on Fedora 8, it is basically the same, except that the menus are ordered in this way: System > Preferences > Personal > Preferred Applications As a side note, perhaps related.....typing in about:config into Firefox's URL bar brings up all kinds of interesting options for Firefox. Haven't played around with it yet at all, but came across it in my google search for how to set my mail client.