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.

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:

http://technet.microsoft.com/en-us/exchange/bb288485.aspx (http://technet.microsoft.com/en-us/exchange/bb288485.aspx)

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:

322756 (http://support.microsoft.com/kb/322756/) 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:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIS\<ServerName>\Public-<GUID>
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.