If your users aren't receiving any email notifications, please check your Notification Settings to make sure that the Email notification has been enabled.
From the Notification settings screen, you can see each available notification and if the Notify by System / Notify by Email is Active or In-Active. If you have integrated with Slack or Microsoft Teams you'll also see the channel dropdown that we'll post messages to.
We always recommend you keep the General Notifications setting enabled for System and Email. There are processes such as the user list exporter which use this function.