You can configure from one to five notification plug-ins.
Messaging Server provides a plug-in library at the following default location:
You use the configutil utility to specify parameters for a plug-in and to point the plug-in to the library of executable code.
If you specify more than one plug-in, each plug-in produces notification messages independently of the others. For example, if two plug-ins are configured with a delete-message parameter, and a message is deleted from a user's mailbox, both plug-ins will produce a notification message.
By configuring multiple plug-ins, you can take advantage of different message-distribution patterns for different purposes. For example, you could configure three different plug-ins to produce messages
To a queue (using Message Queue)
To a topic (using Message Queue)
To the Event Notification Service