If you deal with purchase orders, and you want to make sure that you receive emails when purchase orders are generated, then here's how to do so.
1. Make sure that all the users that want to receive notifications have a properly defined e-mail address. Only administrators can access those settings. As an administrator, navigate to Settings, Users, select a user, click Accounts, and check the user's email address.
2. Create a purchase order, then directly add users to the Notifications tab. Whenever the purchase order status is updated, all users under the notification tab will receive an e-mail at the address specified in their respective user page.