Dear mmken,
Sorry for inconvenience, this is by design for Exchange 2007 architecture redesign. There is no way to fix it.
Here are the reasons why:
l AntiVirus Agent will not be able to piece this message together - there’s probably near to 0 agents that have this capability
l In E2K3 Mailbox kept original MIME, so messages of this content type were handled i.e. they gave the original MIME to Outlook Express so it could piece it together
l In E2K7 the architecture has change and XSO discards original MIME - only MAPI is used in Mailbox - so Outlook Express would not know how to piece it together
Regards,
Rock Wang
Rock Wang– MSFT