Whenever if we work with event sink, we need to check the event registration, what're the associated items, its item properties and its importance (whether it is required or not)...
To receive event notifications, you must register with Exchange by creating and saving event registration items.
Event Registration items
An item becomes an event registration item when you set the content class of the item to urn:content-class:storeeventreg.
Note: For more information, we can get more details from the Content Classes article.
The following table defines the event properties for an event registration item http://schemas.microsoft.com/exchange/events/ namespace:
|Criteria Field||No||A Structured Query Language (SQL) Where clause that specifies the conditions that will cause the event to fire.|
|Enabled Field||No||A Boolean value that indicates if an event registration is enabled.|
|EventMethod Field||Yes||Defines which event or events cause notification.|
|MatchScope Field||No||Defines where the event will fire relative to where it is saved.|
|Priority Field||No||The priority of the event. See Event Notification Priority.|
|ScriptUrl Field*||Yes||The name of the script if the event is a script being run by The Script Host Sink.|
|SinkClass Field||Yes||The class identifier (CLSID) or progID of the object that contains the event sink.|
|TimerExpiryTime Field**||No||The time to end an OnTimer event.|
|TimerInterval Field**||Yes||The interval, in minutes, between OnTimer event notifications.|
|TimerStartTime Field**||Yes||The time at which Microsoft® Exchange begins notifying event sinks of the OnTimer event.|
* This field is required only if you use a script to handle the event.
** This field is used only for the OnTimer event.