Yahoo has introduced a new system that allows users to log in to their own accounts with Yahoo's mobile app without entering a password. The new system only works for people who have a profile with the Account Key system and have installed the Yahoo Mail app on their smartphone. Users get a message pushed to their phone every time someone tries to sign in to their Yahoo account.
The message lists which browser has been used, the location of the device being used to seek access, as well as the date and time. The user simply gives a finger tap on a "yes" button to approve.