Yahoo enables you to link your Facebook account with Yahoo, so you can seamlessly log in to Yahoo using your Facebook details. This gives you quicker access if you're already logged into Facebook, and you'll also be able to use Yahoo Messenger to chat on Facebook. By clicking the Facebook login option, you are automatically logged into Yahoo Mail without entering further login information.
Browse to the Yahoo Mail page (see Resources). If you're not already logged in, you'll be redirected to a login page.
Click "Facebook" in the "Sign In With" section. If you're already logged in to a linked Facebook account, you will be automatically logged into Yahoo Mail.
Click "Log In With Facebook" in the pop-up window. If you're already logged into an unlinked Facebook account, this may not be necessary. If you're not already logged in, enter your Facebook login details and click "Log In."
Click "Allow" when asked for permission to access Facebook Chat, or "Skip" to deny access. Allowing access enables you to chat in Facebook using Yahoo.
Enter your Yahoo username and password, if requested, and click "Sign In" to link the accounts and access Yahoo Mail. After linking the accounts, you will not need to enter your Yahoo login details when choosing to log in using Facebook.
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