Firefox can open your default email application like Outlook or Thunderbird when your click on mailto: links on a web page, but Firefox 3 RC1 can also use a web based email service like Yahoo! Mail or Gmail to open those links.
Selecting Yahoo! Mail as your default email application in Firefox 3 is fairly simple. You just have to go to Tools > Options > Applications and choose Yahoo! Mail from the dropdown list for "mailto". Oddly, Yahoo! Mail is the only web application available to choose from, which renders that feature unless for Gmail users.
Lifehacker points out a little trick to add Gmail. Here’s how:
- Type about:config in your address bar, and Firefox will show you "This might void your warranty". Just ignore and click on the "I’ll be careful, I promise!" button.
- Type
gecko.handlerservice into the filter field and find "allowRegisterFromDifferentHost". Double click that entry to change it from false to true. - Now copy this code into your address bar: javascript:window.navigator.registerProtocolHandler("mailto","https://mail.google.com/mail/?extsrc=mailto&url=%s","GMail")
- A message will popup asking if you want to add Gmail. Say yes and that should do it.
[Via: Download Squad]

wrote, on May 23rd, 2008
This is very useful advise. Thank you.
wrote, on May 23rd, 2008
That’s a neat tip there but I still struggle to get to grips with Gmail. Maybe it is the message grouping, maybe I am just old fashioned and love Outlook.
Is Firefox 3 stable and bug free now?
wrote, on May 24th, 2008
Thats cool, I didn’t even know FireFox had a release 3 candidate till I read your post. I always tend to avoid clicking on mailto tags simply because it always opens up my Thunderbird email client.
wrote, on May 25th, 2008
I don’t think it is necessary for if you have the google toolbar then you can get to gmail with the click of a button. This info is useful though.
wrote, on May 26th, 2008
Great piece of advise dude really helpful …
wrote, on May 28th, 2008
Nice one! Most everybody has a web based email account of some sort, and the ability to integrate it with Firefox in this manner just makes one’s life so much easier! Thanks for the tip!
wrote, on June 2nd, 2008
I great stuff! I did not know you could do that. Yet Google toolbar should pretty much do the same thing for you.