How can I make Yahoo! Mail my default email application?

The Yahoo! Default Email Application is a small 60KB download that allows you to set Yahoo! Mail as your default email application in Microsoft Windows. For example, in Internet Explorer it lets you access your Yahoo! Mail account from any email link on a web page, as well as from the "File/Send" menu or the "Mail" button on the IE toolbar. It also allows you to send a file using Yahoo! Mail directly from Microsoft Word, Excel, and PowerPoint. It's perfect for Yahoo! Mail power users who would like easier access to their Yahoo! Mail accounts.

To install the program:

Go to this help page(http://help.yahoo.com/help/us/mail/ext/ext-11.html).
Check to make sure your system meets the requirements listed.
Click on "Continue." The program will automatically install on your hard drive and set Yahoo! Mail as your default email application.
After the download is complete, you'll have the opportunity to add links or shortcuts to Yahoo! Mail from your desktop and "Quick Launch" menu.
Once this application is installed, when you send files from Word, Excel, or PowerPoint, you'll be taken to the attachments interface in Yahoo! Mail. At the top of the attachments page, you'll be told where your file is temporarily stored. You can add the file to your message by clicking on "Browse" to find it in the location indicated and then attaching as usual.
If you want to switch your default mail application back to another email program, just click on "Tools" and then "Internet Options" in your Internet Explorer toolbar. Then click on the "Programs" tab, and use the pull-down menu to select the default email application you'd like. From there, click on "OK," and your changes will be saved.

The Yahoo! Default Email Application can be installed on a PC running Windows 9x, Windows Me, Windows NT, Windows 2000, or Windows XP. It works with Internet Explorer 4.0 and greater.