Just to check a few things,
You did run the wizard to enable this feature, start the Event Notifier Config, in the first screen you need to configure your from address and mailserver. You can access this mailserver from the server?. Next configure the destination adresses.
Now select the alerts you would like to receive. Now to set the threshold, open the System Management Homepage. Go to Tasks> FileSystem Space Used. Here you can set the Thresholds if you have java installed. So run this from a system that has java installed.
By the way, if a threshold is crossed a trap is send and the event should arrive with relative speed...
