Task lists can be set up to notify a person of an assigned task.
To enable a task list to send e-mail notifications, configure the list on the Advanced
Settings page by selecting Yes for E-mail Notification:
The person to whom the task is assigned will receive a notification with a link to the document.
The person assigned the task receives an e-mail notification like the preceding one. When clicked, the link in the notification opens the task to be completed.