If Microsoft Outlook 2016 or Outlook 2013 is deployed by using the Microsoft Office Customization Tool (OCT) in Windows 10, Outlook 2016 or Outlook 2013 won't display new email desktop alerts (toast notifications).
A new Windows requirement for toast notifications is introduced in Windows 10, version 1607, and it is enforced starting with Windows 10, version 1709. The Windows requirement specifies that an application's shortcut on the Start menu must contain an AppUserModelID tag. However, the Outlook shortcut that's created by the OCT doesn't contain the AppUserModelID tag, so toast notifications aren't displayed.
For desktop applications that send toast notifications, you must include the AppUserModelID tag of your application's shortcut on the Start screen each time that you call the CreateToastNotifier method. If you don't do this, your toast notifications won't be displayed. For details, see Quickstart: Sending a toast notification from the desktop.
To work around this issue, follow these steps:
Perform a Windows installer (MSI) installation of Outlook without using the OCT. Then, the Outlook shortcut that contains the AppUserModelID tag will be created in the following location:
Copy the new Outlook shortcut, and deploy it on the computers that have the issue.