You define your alert policies in Enterprise Alert in order to notify users under certain conditions. Now, it might happen that no alert policy triggers. In this case, in Enterprise Alert you can configure an email address for sending out an email notification if no policy has triggered for an incoming event. You can configure this under “Alerts” –> “Alert Settings” –> “If no alert policy applies, forward event information to”:

This functionality is useful in order to see if you might be missing relevant alerts, i.e. to see if you need another alert policy for handling those un-handled events.