This feature (example shows MS Outlook 2007) allows us to edit an email message which is an already sent one. By nature, it’s not editable. However, Microsoft offers a feature through which one may edit it. This feature should not be abused though.
Open the email which has to be edited. Select Message tab > Actions group > Other Actions drop-down > Edit Message.
The keyboard shortcut for the above set of action is: Alt H, X, E.
Written by Arun Sarathy.