The only thing I can think of would stop the notifications completely until the reset condition were met and then you'd get the reset message. Under Trigger Actions, edit your Send E-Mail/Page action. On the Alert Escalation tab where you set up the escalation to send a notification every 30 minutes, there should be a check box that says Do not execute this Action if the Alert has been Acknowledged. If you check this box and then go to the alerts tab in your Orion web site, you should see all of your active alerts listed. Check the box next to the alert you want to stop receiving trigger notification from and click the Acknowledge Alerts button. This will stop the trigger alert emails from being sent, but you'll still receive the reset email when the link comes back up.
Hope this helps!