gmail mailto firefox.pngEarlier this week we showed you how you could take advantage of Firefox 3’s built-in support for web applications. To be more specific we demonstrated how you can preview iCal calendars using, and thanks to Lifehacker it looks like you can do the same thing for MailTo links.

By default Firefox 3 includes support for Yahoo! Mail with the MailTo links, but using any other email service will require a little bit of work. So below we have instructions on registering either Yahoo! Mail or Gmail as the default handler for MailTo links.

Here’s a MailTo link that you can test the new system on once you get it all setup:

–Yahoo! Mail–

Mozilla made it easy for all of the Yahoo! Mail users out there by including it as on option out-of-the-box. Here’s what you have to do if you’re using Yahoo! Mail:

Open the Firefox preferences, switch to the Applications tab, and look for the “mailto” option in the list. Next to it you should see a drop-down menu, and when expanded there should be an option to Use Yahoo! Mail:

yahoo mail firefox 3.png


  1. Type about:config into the address bar, and change the gecko.handlerService.allowRegisterFromDifferentHost value to true by double-clicking on it. You don’t need to restart your browser after doing this.
  2. Click this link to add Gmail as the MailTo handler. It’s just a snippet of JavaScript.
  3. You should see a little bar pop down from the top of the window asking for permission to have Gmail handle your MailTo links. Click the Add Application button.
    firefox mailto.png
  4. Go back to about:config and set the gecko.handlerService.allowRegisterFromDifferentHost back to false. If you don’t do this any website can attempt to register protocol handlers in Firefox 3, which could pose a security issue.

Note: If clicking on a MailTo link opens an external application (or another service) you’ll need to refer to the steps under the Yahoo! Mail section above for changing the default handler to Gmail.