There are two ways to do this. The first way is to add a Yahoo! AddressGuard link into your "Links" (Explorer) or "Bookmarks" (Firefox) toolbars in your browser window. Click here to learn how.
The second way is to download the Yahoo! Toolbar, a handy suite of tools from Yahoo! that lets you do lots of Yahoo! things from anywhere on the Web, like searching, or clicking right into your Yahoo! Mail account…or making an Yahoo! AddressGuard disposable address! Download the toolbar here.
Now that you have a handy link to Yahoo! AddressGuard right in your browser window, you can make a new disposable address whenever you really need it—at the moment an e-commerce site asks for one, for example. Click the Yahoo! AddressGuard link—either in Firefox's "Bookmarks" toolbar or Explorer's "Links" toolbar, or the "Mail" "Add disposable address" link in the Yahoo! Toolbar. Bingo!
This pops up a window allowing you to create a new disposable address. If you're not already logged in to your Yahoo! Mail account, you'll be asked to log in using your Yahoo! ID and password. When you're done creating your disposable address, you can easily copy and paste it into the web site you're visiting.
The "My Disposable Addresses" menu item in the Yahoo! Toolbar pops up a small window allowing you to review your existing disposable addresses. You can edit them, add a new one, or simply use this to recall which existing address is a good match for the site you're visiting.