In Firefox 3, by default, when user click on an email address or a URL link location that starts with mailto: protocol, the default email client, such as Microsoft Outlook, Outlook Express or Windows Mail will be opened to allow user to compose and send email to the specific recipient’s mail address.

If you prefer to use web based Yahoo! Mail as your default email client, and want to let Yahoo! Mail handles all mailto: protocol, so that the automatic e-mail message composing and email sending will be done via Yahoo! webmail interface, Firefox 3 provides a very easy to associate the mailto: link with Yahoo! mail web-based interface, in fact, it’s a built-in integration.

  1. Go to Tools -> Options.
  2. Click on Applications tab icon.
  3. Locate and click to highlight mailto Content Type, and at the corresponding drop down box of Action, select Use Yahoo! Mail.
  4. Click OK.

After change, whenever a mailto: link is clicked, the email address will be sent to Yahoo! Mail account Compose web interface, with recipient automatically set at the clicked e-mail address. Of course, user have to enter user name and password credentials first if he or she hasn’t already logged in.

Note: It’s also possible to set Gmail as the default mailto: handler at Firefox 3.