If you’re using a SharePoint task list and you’d like to send a notification by email for who has a task assigned, you need to do just a simple step.
Access your SharePoint Site, click on tasks in the left side menu, now click on List on the ribbon and then List Settings.
Into List Settings, click on Advanced Settings and Enable E-mail Notification, and that’s it.
Now every new task created or modifications made, the person assigned to the task will receive an email.
Simple and useful