I set the alert scheduled every 5 minutes. When alarm occour, i receive mail as long as the alarm persist (every 5 minutes with same timestamp)
I don't want this, i would like receive mail once (when alarm occour the first time).
*/5 * * * *
Is greater than 0
in the alert settings, try to check the Trigger "Once" box below the trigger condition and then the Throttle (set to a time you like)