You can configure a new alert on the detection of a new neighbor. A New neighbor detected alert is available in the Heartbeat section of the Configuration / Alert page on an agent. You can associate it with the definition of an advanced expression in order to precisely filter the characteristics of the neighbor that will trigger the alert. The list of available filterable elements is like the columns on the Network neighborhood page. This data is accessible from the "event" object.
ip, mac, netbios, updatedAt, createdAt, macVendor, detectedOs, hasCorrespondingAgent
Example: I only want to be alerted for HP vendor neighbors with Windows as detected OS:
event.macVendor == 'HP and event.detectedOs ==' windows'