How can I change email subject?

Is there a way to change the email message 'subject' on Entourage similar to Outlook (2007 and 2003) when it is on the Exchange server?

In Outlook I can click on any message in my received email folder (note this is not a new email) and on the subject line I can replace the subject or add to it. I use this sometimes to make notes on messages I have to come back to or clarify what's in the email for easier reference.

I can't seem to find this feature in Entourage even though it does support Exchange server as well. I seem to be able to 'edit message' as Outlook also allows although I have not checked yet if this propagates to the Server as well.