Beside create forwarding rules in Content Filtering page,you can just create such rules inside user's Forwarding tab as below guideline:
1) Log into your SmarterMail interface
2) Navigate to Setting -> Expand 'My Setting' ->Click User setting -> Click 'Forwarding' tab -> And fill up the address to receive the copy of incoming mails.If more that one recipient,please add all the address separate with comma.Then click Save.
Done.