Hi,
In case if you have applied policy for receiving Notification, then you would surely receive Notification for ALL Risks.
At this point there is no way you could just exclude 1 type of Threat for not receiving Notification.
However, you could exclude Tracking cookie for being scanned, which would be then be not detected as a Threat.
OR create a Centralized Risk Exception.
How to add a Centralized Exception for a detection that is not included with Known Security Risk Exceptions in the Centralized Exception Policy.
http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2008100706493648