Firefox 3 has a great new feature where you can set it up so that when you click on an email link in your browser, it opens a web-based mail application to send the mail instead of a desktop application. The only down-side to this is that the only web-based mail application supported with the released version of Firefox 3 is Yahoo Mail. But don't despair. If you are a GMail user, here are the steps to take to get Firefox 3 to open mail links in GMail.

- In the Firefox 3 address bar, type about:config and click through the warnings.

- Scroll down to find the Preference called gecko.handlerService.allowRegisterFromDifferentHost. The value will be shown as false. Double-click on this entry to toggle the value to true.

- You then need to copy a chunk of Javascript into your address bar and hit Return so that it runs. The Javascript you need varies depending on if you are a Google Apps users or not. If you use Google Apps, your Javascript is this:

javascript:window.navigator.registerProtocolHandler("mailto","https://mail.google.com/a/YOURDOMAIN/mail/?extsrc=mailto&url=%s","GMail")

where you replace YOURDOMAIN with your actual domain name. If you do not use Google Apps or you have no idea what your domain is, use this Javascript:

javascript:window.navigator.registerProtocolHandler("mailto","https://mail.google.com/mail/?extsrc=mailto&url=%s","GMail")

- You'll get some warning from Firefox about adding an application handler and you'll be given a button at the top of the browser with the text Add Application in it. Click that button.

- Go back into about:config and find gecko.handlerService.allowRegisterFromDifferentHost again and double-click on it again to set it back to false.

You have now added GMail as an application handler for mail links. When you first click on a mail link, you'll be asked what application you want to use to handle mail links and GMail will be one of the options. You can choose it then and check the box to remember this so that you don't get asked this again in the future. If you have already checked this box for a different mail option and you are no longer asked which application to use, you can open the Preferences for Firefox and change this in the Applications tab.