When an event is triggered in a monitored folder, the EventDetails object is automatically passed to the Event Service script. This object provides access to the following three intrinsic objects:
The EventDetails object contains information on what has been posted, changed, or deleted, and what folder the event happened in.
Receiving the EventDetails.Session object provides the application with a valid MAPI (or CDO) session. This is equivalent to logging on, so you do not need to log on explicitly. The Session object is the topmost object in the CDO object hierarchy, so it provides access to the entire object model of CDO. Now that we are logged on, we can look in any folder, any message, any property on the message, or any fields collection.
When an application is logged on to MAPI (or CDO), it is logged on as someone. Whoever wrote and installed the Event Service script owns the account you are logged on as. For more information, see Processing Folder Events in Script.