Reply and Forward Options
To customize these options, do the following:
1. On the File tab, choose Options:
2. In the Outlook Options dialog box, choose the Mail tab and then scroll to see the Replies and forwards group:
3. Using the drop-down lists in the Replies and forwards group, specify whether Outlook should include the original message text when you reply to or forward a message.
4. Click OK in the Outlook Options dialog box.
See also this tip in French: Options de réponse et de transfert.