XCLN: Unable to Save Changes to Attachment in Private Msg.

SYMPTOMS

When you receive a Private (read-only) mail message with attachments, you can view and modify the attachments; however, you can not save the changes to the original message.

When you close the Private message, and you made changes to the attachment, you will get the following message:

If you make modifications to attachments in a read-only message until he closes the note and gets the message:

   This message has been modified but this message is read-only.
   Do you want to discard changes?