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Public folder message classes

Understand Exchange's IPM.Note and IPM.Post public folder message classes and how their functionality varies from Exchange 5.5 to Exchange 2000 and 2003.

Exchange identifies different types of messages -- e-mails vs. folder posts, for instance -- by assigning them a message class. E-mails typically use the message class IPM.Note, while posts to a public folder have IPM.Post. Message classes not only determine how a message is presented to the user (i.e., which form to use), but how to handle it (i.e., expiration, tracking, etc.).

SMTP mail sent to a public folder in Exchange 2000 and 2003 is defined as IPM.Post. However, in Exchange 5.5, SMTP mail in a public folder has IPM.Note for a message class. Ergo, messages sent to a public folder in Exchange 2000/2003 will have their format changed. If you want to archive messages sent to public folders without changing their format, you'll need to make some changes to Exchange by applying a hotfix and editing the registry.

For Exchange 2000, first obtain the August 2004 Exchange 2000 Server Post-Service Pack 3 update rollup. For Exchange 2003, the hotfix for this problem is only available from Microsoft Product Support Services; contact them and ask for fix 817809.

Once you have the hotfix in place, edit the following registry key:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIS\<servername> \Public-<GUID>

<servername> is the name of your Exchange server and <GUID> is the unique ID generated for a specific public folder database. (There may be more than one, so each one needs to be set individually. The upside of this is that you can have some folders preserve mails as IPM.Note and have some folders convert mail to IPM.Post.)

Create or edit a DWORD value, name it Incoming defaults to IPM.Note and then set this value to 0 to convert all incoming messages to IPM.Post. Set it to 1 to preserve SMTP e-mails sent to public folders as IPM.Note.

About the author: Serdar Yegulalp is editor of the Windows 2000 Power Users Newsletter and a regular contributor to

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