How to add an email forwarding in Exchange 2003
Very easy to do:
Using Active Directory Users and Computers on a machine with the Exchange admin tools installed, create a mail-enbled contact object in the Active Directory and assign it the user's desired forwarding address ("[email protected]", etc).
Add the newly-created contact as an alternative delivery recipient on the "Exchange General" tab of the properties of the user who wants the email forwarding by clicking "Delivery Options", selecting the "Forward To" radio button, clicking "Modify", and choosing the newly-created contact from the AD. Optionally check the "Deliver messages to both forwarding address and mailbox" if you so choose.
This is relatively easy to accomplish on Exchange. It can also be turned on in the Outlook client with rules.