Hi,
Email notifications are sent to every user that is subscribed to the object, and are sent when the object is created, modified, etc. Object's creator is always subscribed to the object, and more users can be set as subscriptors when adding or editing an object, clicking on 'Subscribers' link and selecting users.
Make sure you also have configurated mail settings in 'Administration / Configuration / Mailing'
hope this helps,
If you have any other questions don't hesitate to ask.
greetings.