Yahoo began its assault on the password in March with SMS-based two-factor authentication, and now the company wants to finish what it started. On Thursday, Yahoo announced Yahoo Account Key, a password-less method of logging in to Yahoo Mail that will roll out to other Yahoo services in the coming months.

Account Key effectively works like two-factor authentication, allowing you to authorize new logins via your smartphone or tablet. The only difference is Account Key is not a secondary back-up measure that kicks in after you've entered your password: it is the primary way you access your account.

Yahoo Account Key in action.

Yahoo's approach doesn't rely on the user entering a code received from an authenticator app or SMS. Instead, when you try to log in to Yahoo Mail a notification gets sent to your mobile device without entering a password.

From there you can either hit a Yes or No button to authorize access. This is similar to how Twitter handles second-factor authentication, but again, Yahoo's approach is the primary way you will access your account.

Account Key is rolling out alongside a new Yahoo Mail mobile app that features a new look, a faster way to search for items by sender, keyword search suggestions, and an improved compose interface.

Yahoo Mail is also adding support for Outlook.com and AOL email addresses, allowing you to access these accounts inside Yahoo Mail, including on the revamped mobile app. Multiple account support must first be enabled on the desktop and is only available to U.S. users at launch.

The refreshed Yahoo Mail mobile app is available now worldwide on iOS and rolling out to Android users over the next few weeks.