Major annoyance: clicking on mailto links in Firefox doesn't open the email app I want to use, KMail. Another related major annoyance: going to File > Send Link in Firefox doesn't open the email app I want to use, KMail. The solution? Find your profile folder for Firefox; more than likely you'll find it at /home/[username]/.mozilla/firefox/[random-letters-n-numbers]/. In that folder, if you have a file named user.js, open it with a text editor; otherwise, create it and open it with a text editor. Add the following lines:

// File > Send Link uses Kmail
user_pref("network.protocol-handler.app.mailto","kmailservice");

The 1st line is a comment describing what we're doing; the 2nd line performs the magic. Save & close user.js, restart Firefox, go to a web page, and choose File > Send Link. An email message using KMail should open. Ahhhhh!

(And yes, I wrote a book about Firefox - Don't Click on the Blue E!: Switching to Firefox - that you might find interesting.)

(Check out all of our posts on Firefox and KMail.)