Internal users, that is, users in your own company that have access to your Intranet, are not sent notification e-mail messages automatically. The have to actively subscribe to a notification in order to receive notifications. It is very important to note that:

Notifications can also be sent to external recipients, such as business partners. These recipients are, contrary to the internal ones, set up explicitly.

The topic How to Subscribe describes the subscription interface and what end-users need to know about it.