There are various methods to configure push notifications in D365. It depends on customer's business process requirement –emails can be triggered on certain actions, changes, approvals.
Dynamics 365 allows to send emails via workflows. We use workflows to send email notifications for various functionalities such as:
Depending again on business requirements and specific use cases for the requirements, you might also consider using Microsoft Flow to send Flow notifications. We have implemented Microsoft flow for notifying user of record created through PowerApps
'Notify 365' is also a very convenient option. We have not used it for any customer, but we have tried it on trial environment. It is easy to configure but keep in mind it also required basic knowledge of workflows. You can refer below mentioned links to find more details on 'Notify 365'
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