Classifying Messages in Exchange Server 2007, Part 1

Posted on January 7, 2009 by Brien Posey in Exchange Server with 0 Comments

By now you’re probably familiar with the idea that Exchange Server 2007 is designed in such a way that every message flows through a central pipeline.  Microsoft designed Exchange Server in this way so that there would be a central portal through which all messages flow, and therefore messages could be analyzed in certain types of content could be acted on by transport rules.  Although Exchange Server gives you a great deal of flexibility in the types of transport rules that you can create, imagine how much more powerful the transport rules could be if Exchange Server could actually understand what the messages were all about.  I’m not talking about just knowing who the messages going to, or where it came from, or whether or not the message has been flagged as important, but rather the message’s purpose.

Believe it or not, Exchange Server 2007 has been designed so that users have the ability to categorize messages.  You can then create transport rules that are based on message classifications, rather than trying to create transport rules that guess what messages purpose might be based on some of the more common attributes.

Good News and Bad News

As you can imagine, message categorization can be a very powerful tool to help you to manage the messages flowing through your organization. Before I show you how message categorization works though, I have some good news for you and I’ve got some bad news.

The good news is that Exchange Server has several classifications built in that you can start using right away. If the built in classifications are insufficient then you even have the ability to create custom classifications.

The bad news is that the message categorization feature only works with Outlook 2007 and OWA. Users who are running Outlook 2003 or other older versions of Outlook will not be able to use message categoriazation. Furthermore, message categorization is not enabled by default in Outlook.  Enabling message categorization and Outlook is a manual process that involves exporting an XML file from Exchange, and then using that XML file to modify the registry on each workstation that is running Outlook.  As if this process were not cumbersome enough, it must be repeated each time that an additional classification is created.

Default Message Classifications

As I mentioned earlier, there are several classifications that are built into Exchange Server 2007.  The table below lists these classifications and their purpose:

Message Classification Purpose

Company Confidential The Company Confidential classification is intended for use in situations in which the contents of a message need to be treated with secrecy.  Simply assigning this message classification does not enforce any additional security on the message, but it does inform the recipient that the contents of the message are not to be disclosed to anyone else.
Company Internal The Company Internal classification tells the recipient that the message contains sensitive information that may be discussed with other employees, but that is not to be disclosed to the outside world.
A/C Privileged The A/C Privileged classification indicates that the message contains information that is protected by attorney/client privilege. Again, simply assigning a classification does not provide any additional security to a message, but you can use this classification to flag all communications to or from the company’s legal department so that those messages are protected against being subpoenaed.
No Restriction The No Restriction classification is the classification that is assigned to all messages by default. As the name implies, it conveys to the recipient that there are no restrictions on the message.
Attachment Removed The Attachment Removed classification is used internally by Exchange Server, and is invisible to Outlook and to OWA clients. This classification is used to flag messages that have had an attachment removed because the attachment contained malware.

Displaying Message Classifications

As you have probably guessed, message classifications are not exposed through the Exchange Management Console and are therefore only accessible through the Exchange Management Shell.  I will talk a lot more about message classifications in Part two of this series.  In the meantime though, if you would like to see which message classifications Exchange Server is currently aware of you can open the Exchange Management Shell and enter the following command:


When you do, Exchange will display information similar to what is shown in Figure A.

Figure A The Exchange Management Shell displays the message classifications that are currently defined.


In this article, I have explained what message classifications are, in which classifications are built into Exchange Server 2007. In the next part of this article series, I will continue the discussion by showing you how to use message classifications.

Got a question? Post it on our Exchange Server Forums!