Turn on desktop email notifications

Windows

1. Select File > Options > Mail.

2. Under Message arrival, select or clear the Display a Desktop Alert check box and then select OK.

   Microsoft support has an article as well as video here.

MAC

1. On the Outlook menu, click Preferences.

2. Under Personal Settings, click Notifications & Sounds.

3. Under Message arrival, choose the settings that you want for new messages.

   Microsoft support has an article as well as video here.