Two things should happen when certain events occur, such as a calendar appointment, instant message or a new email.
One is that the event should be added to Notification Center and the other is a pop-up notification in the top right corner of the screen. Unfortunately, this does not happen for some people with the Mail app on the Apple Mac. Why?
If you use the latest version of Chrome for browsing the web on your Apple iMac or MacBook, you will have noticed a new icon in the menu bar, a bell icon which is used to access notifications and Google Now. When Chrome is running, and it doesn't have to be on the screen, it can be minimised, clicking this icon will display a notifications panel that is similar to what you would see on an Android phone. Is it useful? Do you need it?