Enterprise Vault (EV) uses an item's Message Class as the first criterion to determine whether or not the item is eligible for archiving. The Exchange Message Classes tab on the Directory Properties page holds the master list of all Message Classes that can be included for archiving or excluded from archiving, while each Exchange Mailbox Policy holds an actual working list of which Message Classes are selected for archiving in that Policy.
 

How Message Classes work

Every item in Outlook is based on a form. When you double-click on an item to open it, Outlook queries the item's Message Class property to determine which form it is based on. For example, when you open a mail item, Outlook knows through the message class property that the mail item should be opened with a Message Form. The name of the message class containing the definition of the message form is IPM.Note. The figure below shows the Message Classes for the built-in Outlook forms.
 

Form	Message Class
Appointment	IPM.Appointment
Contact	IPM.Contact
Distribution List	IPM.DistList
Journal	IPM.Activity
Message	IPM.Note
Post	IPM.Post
Task	IPM.Task
Documents	IPM.Document

Outlook also allows the creation of new forms and Message Classes, as well as the extension of existing built-in forms and classes. The extension class is named by appending to the name of the base class. For example, the Outlook appointment class (IPM.Appointment) were extended to include a special form for holiday appointments, the newly created class might be named IPM.Appointment.Holiday.
 

Enterprise Vault Message Class behavior and settings

From an Enterprise Vault perspective, all message classes can be processed, whether built-in or newly created, but not all message classes are enabled by default. Message class processing is controlled in two places. To be processed by EV's archiving task, a Message Class must first be entered in the list on the Exchange Message Classes tab of the Directory's Properties page in the Vault Administration Console. The figure below shows the default Message Classes that are available in a new installation of EV.

 


Custom Message Classes can be added to this area. The asterisk (*) notation indicates that the entry covers the named Message Class and all of its sub-classes (e.g., "IPM.Appointment*" includes both IPM.Appointment and IPM.Appointment.Holiday). An entry in this list is necessary but not sufficient to ensure that a given Message Class is archived.

The Exchange Mailbox Policy contains a tab called Message Classes. This is where the individual Message Classes can be included or excluded from archiving for a given policy. The figure below shows the default selections.

 

When a message class is left unchecked, this means it is explicitly denied from being archived. This will override any 'enabled for archiving' permissions.
 

A Note on Enterprise Vault Shortcuts

EV uses its own custom Message Classes to identify the shortcuts and pending items that it creates as part of the archiving process. EV's archiving tasks contain internal logic to avoid processing these EV items; it is not necessary to exclude these Message Classes by adding them to the list and deselecting them. Attempting to do so may actually interfere with EV's shortcut processing functionality.

A Note on Enterprise Vault Search

To view the archived message of the newly added Message Class on the ReadingPane of Enterprise Vault Search, perform the following steps:

1. Navigate to the \EVSearch\EVSearchClient\Plugins\Common folder.
2. Open the NamedReadingHeaders.common.xml file.
   The file contains the ReadingPaneMessageClassMappings node.
3. Add the newly added Message Class under SupportedMessageClasses in the appropriate ReadingPaneMap as shown below:
   
   
 
   
     
        IPM.Note.Test
        .
        .
        .
     
   
    .
    .
    .
 
 
    .
    .
    .
   

    
4. Restart Internet Information Services (IIS) using the iisreset /restart command on the elevated command prompt.