XFOR: Message Format Differs Between POP and MAPI Clients

When a MAPI client receives messages from the Internet, Internet Mail (also known as IMAIL) converts the original Internet message to a MAPI message properly; and the message would be delivered to the user's inbox. However, if the user tried to read the message through a POP client, the message that the user sees on a POP client may not look the same as it looks in a MAPI compliant client. This problem is evident when POP Client views MIME messages with multipart/alternative bodypart inside a multipart/related.

Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 5.0. This problem has been corrected in the latest U.S. Service Pack for Microsoft Exchange Server version 5.0. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

Internet Mail attempts its best to preserve the original Internet message format when converting a MAPI message (which had originally come in from Internet) to Internet format. If this preservation is complete, the "full fidelity" was being preserved. The described problem indicates that the full fidelity preservation has failed for MIME messages with multipart/alternative bodypart inside a multipart/related. This is causing the message viewed in a POP client to be different than the original Internet message.