Forwarding E-mail to an external account

I am new to Exchange 2000 and need help with an issue that may be small. We have a local AD account with an Exchange mailbox that represents four users on another E-mail system altogether. What I would like to do is set up a forwarding address so e-mail sent to this address would be sent via smtp to the four external e-mail addresses. Being an old groupwise admin i want to set up the equivalent of 4 external entities and put them on a distribution list. Have no idea where to start… any help????