Yahoo! is introducing a new user authentication feature which is similar to Google’s 2-step verification method to block all account hijackers from unauthorized access and it's called ‘Second Sign-in Verification'.
Once the feature is turned on, any suspicious account sign-in attempt will be challenged by a second sign-in verification beyond the initial password validation. To confirm the legitimacy of the sign-in attempt, you or the hijacker will have to answer your account security question or enter a verification code that will be sent to your mobile phone .Account hijackers will be blocked since they neither know your security answer nor possess your mobile phone.
Once the feature is turned on, any suspicious account sign-in attempt will be challenged by a second sign-in verification beyond the initial password validation. To confirm the legitimacy of the sign-in attempt, you or the hijacker will have to answer your account security question or enter a verification code that will be sent to your mobile phone .Account hijackers will be blocked since they neither know your security answer nor possess your mobile phone.
How to Enable Second Sign-in Verification in Yahoo
Log in to Yahoo! Account Info and Enable second sign-in verification. As part of the process, you will be required to add a mobile phone number to your account and verify it via SMS.
For the time being, the option is being rolled out only for users from the US, Canada, the Philippines and India. Yahoo will be extending this feature gradually to all worldwide users by March 2012.