is controlled from the setting mentioned at the bottom of your screenshot. If you are using the 6.5 console (since those directions are for the 6.0 console) you would go to configure - notification server - advanced settings. Uncheck 'system scalability check'.

I have unchecked that box and it is still sending me messages.  Any other ideas?

if the email is really coming from that notification policy, and you unchecked it, it shouldn't be sending you anything else. Check under the main configuration tab, or view (6.5), and there should be  a notification policy folder under the server settings, notification server settings (or perhaps notification server infrastructure). Review those policies for applicability as wel.