In a Microsoft Exchange Server 2007 SP2 environment, you use the IMAP4 APPEND command to add a message item that has new X-headers. When the message item is retrieved by IMAP4 or retrieved by POP3, the new X-headers do not appear. However, the new X-headers appear if the message item is retrieved by MAPI or by Outlook Web Access (OWA) clients.
Note When this problem occurs, the HeaderPromotionModeSetting parameter is set to MayCreate by using the Set-TransportConfig cmdlet.
This problem occurs because the new X-headers are not promoted to named properties by the Exchange Server 2007 server. Therefore, there is no data for the new X-Headers can be converted from MAPI to MIME when POP3/IMAP4 clients try to retrieve the message item.
To resolve this problem, install the following update rollup:
2602324 Description of Update Rollup 5 for Exchange Server 2007 Service Pack 3
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about the Set-TransportConfig cmdlet, visit the following Microsoft website: