A Microsoft Exchange Server 2010 user opens a signed mail message that includes an attachment. If the user opens the signed mail message by using an Office Outlook 2003 client, the attachment is not visible. However, the attachment is visible by using Outlook 2007 or by using Outlook 2010.
Note There is no paper clip icon which indicates that the signed mail message has an attachment in any version of Outlook.
To resolve this problem, install the following update rollup:
982639 Description of Update Rollup 4 for Exchange Server 2010
To work around this problem, the user may follow these steps:
Open the signed mail message in Outlook 2003 and then click File.
Click Save Attachments.
Then, the user can save the attachment.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.