A property of the item called message class determines the form the item uses. This application can help you to change the message class for incoming messages from the default to custom one. For example, you create a custom Outlook form with IPM.Note.Sales message class and you need that each message e-mailed to your Exchange Sales mailbox will be converted to your custom form (IPM.Note.Sales) immediately after receiving to display information in a Sales custom form. See a good article that describes an Exchange 5.X - based application to support group mailbox functionality: Implementing a Group Mailbox or Public Folder.
Using ChangeMessageClass application you can implement the same functionality in your Exchange 2007 Server based system.
The application also can delete permanently the incoming messages associated with a certain message class. For example, you can delete all nondelivery reports whose message class is Report.IPM.Note.NDR before delivering them to the user's mail Box.
The application is an Exchange store event sink.
Benefits
Message type conversion is processed instantly, before any rules are applied
You can set up ChangeMessageClass on per-mailbox basis or as a "store-wide" application, i.e. it will work on each user's Inbox in the certain Exchange 2007 mailbox store
The application is server-centric, so you do not need to install any extra software on the client side
