Account Key uses push notifications to provide a faster way to sign into email using your mobile device.

Once a user has linked the Yahoo account with the smartphone app, they will receive a push notification upon trying to sign in on the web. The user just has to verify or deny the access on the phone.

"Passwords are usually simple to hack and easy to forget. Account Key streamlines the sign-in process with a secure, elegant and easy-to-use interface that makes access as easy as tapping a button," the company said in a statement yesterday.

"It's also more secure than a traditional password because once you activate Account Key - even if someone gets access to your account info - they can't sign in," it emphasised.

The app has been fully redesigned, Yahoo said, to make it 'fast and responsive'. Yahoo introduced the changes as it turned 18 this month.

The new Yahoo Mail app is available in the Apple App Store as well as Google Play to all global users now.