Setup Yahoo or Gmail as default mail with firefox

link to where info was found

Clicking on a mail-to link in your browser used to launch your email program, and you'd have to wait for Outlook or Thunderbird (or any other email client) to open. What if your primary email address is through Yahoo! or GMail? Firefox 3 allows you to specify a web-based email service as your default email client instead of the default email program on your computer. These are the steps for both Yahoo! and Gmail.

How to Set Yahoo! Mail as Default Email Client in Firefox 3
1. Launch Firefox 3.
2. Go to "Tools" > "Options" on a Windows PC. On a Mac, select "Firefox" and "Preferences" from the Firefox 3 menu or use the keyboard shortcut Command - Comma.
3. Select "Applications" in the Preferences window.
4. Type "mailto" in the "Search" bar.
5. Click on the "mailto" entry.
6. Select "Use Yahoo! Mail" from the drop-down menu. Now whenever you click on an email address with a "mailto" link, Firefox 3 will use Yahoo! mail.

How to Set GMail as Default Email Client in Firefox 3
1: Launch Firefox 3.
2: Log in to your Gmail Account.
3: Copy and paste the following string of code into your browser's address field:javascript:window.navigator.registerProtocolHandler("mailto","https://mail.google.com/mail/?extsrc=mailto&url=%s","GMail") .
4: Click on "Add Application."
5: Quit and relaunch Firefox 3.
6: Go to Firefox's Preferences by selecting "Tools" > "Preferences" on a PC and "Firefox" > "Preferences" on a Mac.
7:Type in "mailto" in the text box next to "Search."
8: Click the "mailto" option.
9: Select "Use Gmail" in the drop-down box. Now when you click on a "mailto" link, Firefox 3 will launch Gmail for you to compose and send your email.