Job Alert emails are only sent when new jobs that match your search are found. If you are consistently not receiving results, you may want to refine your search criteria and set up a new alert for the new search.
If you need to edit or delete an alert, you can do so through the Email Preferences page on your account.
Also, make sure that you have email@example.com as a safe sender for any spam blocking software.
Lastly, be sure to check your spam, junk, or trash folders. Job Alert emails may have been moved automatically.