This article describes where Yahoo! forwards all notifications.

Yahoo! sends all of your notifications to your primary email address. If you aren't sure what your primary email address is or if you'd like to change it, please visit the help article What is the difference between primary and alternate email addresses? to learn more.

Note: You can also view your notifications by clicking the bell icon in the header of some Yahoo! properties. The number of unviewed notifications is shown in the red box to the right of the "bell" icon.