When you send Simple Mail Transfer Protocol (SMTP) mail (mail that is not from a MAPI source) to a Microsoft Exchange 2000 Server or a Microsoft Exchange Server 2003 server public folder, the message class is IPM.Post. In Microsoft Exchange Server 5.5, the message class of a message that is sent to a public folder is IPM.Note. Because of this, if you have a message archiving system where the e-mail messages must be completely stored and not changed or converted, you may not be able to archive messages from the public folder. This article describes an update that you can use to configure the setting of the PR_MESSAGE_CLASS attribute of SMTP messages that are sent to public folders to IPM.Note instead of IPM.Post.
For more information about how to have incoming SMTP messages that are bound for public folders be marked as IPM.Note in Exchange 2000 Server, click the following article number to view the article in the Microsoft Knowledge Base:
Embedded e-mail messages appear as IPM.Post after you configure incoming SMTP messages as IPM.Note in Exchange 2000 Server
The hotfix for the issue that is described in KB article 830961 is provided in KB article 827555.
Exchange 2000 Server
To resolve this issue in Exchange 2000, obtain the hotfix that is described in the following Microsoft Knowledge Base article:
An incorrect number of unread items may be displayed for public folders in Exchange 2000 Server Service Pack 3
Because of file dependencies, the hotfix that is described in Knowledge Base article 827555 requires Exchange 2000 Server Service Pack 3 (SP3) and the August 2004 Exchange 2000 Server Post-Service Pack 3 Update Rollup.
For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base:
How to obtain the latest Exchange 2000 Server service pack
Availability of the August 2004 Exchange 2000 Server Post-Service Pack 3 Update Rollup
Exchange Server 2003
To resolve this issue in Exchange 2003, install Exchange Server 2003 Service Pack 1 (SP1). To obtain Exchange Server 2003 SP1, visit the following Microsoft Web site:
How to configure the new setting
The following information applies to both Exchange 2000 Server and Exchange Server 2003.Important
This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
How to back up and restore the registry in Windows
After you install this update, incoming messages to public folders can have their message class changed to IPM.Note instead of IPM.Post. You can configure this new setting by creating the Incoming registry value in the following registry subkey:
Value name: Incoming defaults to IPM.Note
Value type: DWORD
Value data: 0 or 1
0 (zero) is default (0=false).
The default behavior without the registry key is that incoming messages appear as IPM.Post. If you set the registry key to have a value of 0 (zero), the result behavior is the same as the default behavior, and incoming messages appear as IPM.Post. If you set the registry key to have a value of 1 (one), the behavior changes, and new SMTP mail messages from a non-MAPI source appear as IPM.Note.Important
To enable this functionality you must configure these registry settings on all Exchange servers that host public folders. You do not have to configure these registry settings on Exchange servers that do not host public folders. Additionally, you must configure these registry settings for each public folder database on the particular server where you want to enable this functionality.
After you make these registry changes, you must restart the Microsoft Exchange Information Store service to enable this new functionality. Note
In interoperability scenarios for Exchange Server 2003, you do not have to use this registry setting.
Exchange Server 2007
On a server that is running Microsoft Exchange Server 2007, e-mail messages from the Internet to a public folder come in as IPM.Note. This behavior occurs even when you do not use the "Incoming defaults to IPM.Note" registry value.
This behavior is expected in Exchange 2007. When a message passes through transport, Exchange 2007 assigns a message class of IPM.Note if a message class is not already present. Therefore, when the message reaches the store, it already has a message class. The store's default message class is not used. Note
You cannot require the IPM.Post message class instead of the IPM.Note message class in Exchange Server 2007.