In a Microsoft Exchange Server 2010 organization, you are running workflow applications that access multiple mailboxes and that process email messages automatically. Some of these messages contain attachments. However, you discover that some of these attachments are not visible in Microsoft Outlook and other MAPI clients. Therefore, the workflow apps do not process the messages as expected. Additionally, because users don't see the attachments, they may forward messages that contain sensitive attachments to external users.
This issue occurs because the embedded messages for which name, content-disposition and content-description are not set have the PR_ATTACHMENT_HIDDEN property set to FALSE. Therefore, the attachment is hidden.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.