Message classifications were introduced with Exchange 2007 which seems like ages ago now. They are a piece of metadata which you can assign to messages, for example the intended audience or sensitivity of messages. These message can then be treated accordingly by the recipient or you can leverage transport rules functionality and Rights Management Services to act on or protect these messages.

Let’s assume you have created a custom message classification using the following cmdlet:

New-MessageClassification –Name ‘InternalUseOnly’ –DisplayName ‘Internal Use Only’ –SenderDescription ‘This message is for internal use only.’

When you retrieve the list of message classifications using Get-MessageClassifications you will notice three additional classifications:

Exchange comes with these message classifications which are used by Exchange internally: ExAttachmentRemoved, ExOrarMail and ExPartnerMail. These should not be used by users, let alone be visible. To make them hidden, the PermissionMenuVisible attribute is set to $false for these classifications. This will make them not show up in Outlook WebApp:

Now, using classifications in Outlook is less admin-friendly and requires exporting of classification information and configuring Outlook to read these classifications from a file. In short, the process described on TechNet TechNet to use message classifications from Outlook is as follows:

From the Exchange Management Shell, run the Export-OutlookClassification.ps1 script from Exchange scripts folder, e.g.

& ‘C:\Program Files\Microsoft\Exchange Server\v15\Scripts\Export-OutlookClassification.ps1’ | Set-Content ‘C:\OutlookClass.xml’

Next, copy the XML file to a location on the client or networked location which is readable by Users. On the client, make the following registry changes:

[HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Common\Policy]
"AdminClassificationPath"="c:\\Classifications.xml"
"EnableClassifications"=dword:00000001
"TrustClassifications"=dword:00000001

Note: For the purpose of this example the XML is stored as C:\Temp\OutlookClass.xml . Note that “15.0” is for configuring Outlook 2013, replace with 14.0 for Outlook 2010 and 12.0 for Outlook 2007.

Restart Outlook so it will use these settings. When composing a message you will now see the message classification options appear under Options > Permission:

Apart from the message classification “Internal Use Only” we created, you will also see that Outlook shows the internal classifications by their display name. That should not be happening.

When you open up the Outlook classifications export file, you will spot that it contains all classifications, including the internal ones:

So, what you can do now and what the documentation seems to fail to mention, is that after exporting message classifications you may want to remove the internal classifications “Attachment Removed” (ExAttachmentRemoved), “Originator Requested Alternate Recipient Mail” (ExOrarMail) and “Partner Mail” (ExPartnerMail) from the XML export file. Downside is that message with these internal classifications will not display the related description in Outlook, but that should not be an issue and a better option than users being able to select them.

When you have removed the three entries from the XML file and restarted Outlook, the built-in options will no longer be on the permission menu: