Yes it can be done. Just go to http://forums.digitalpoint.com/profile.php?do=editoptions Then click on Receive Email Notification of new Private Messages And all PM's will be coming to your email as well as in DP.
Seems a bit funny that you'd want to forward your DP messages to your 'friend'. Ever thought of forwarding your own emails to your friend? I reckon that'd work. DP would only send e-mails, notifications, etc... to the registered or currently used email account of the user.