We have just upgraded from Exchange 2003 to Exchange 2010.  No other changes have been made to our network.  No changes were made to user workstations.  Now when users receive emails from Cicso Registered Envelope Service the HTML file attachments seem to be damaged.  It seems as if Exchange 2010 is stripping part of the HTML attachment.  The final error is "Incomplete Payload".  Please let me know if you have any suggestions.