Caveat - This works sometimes (I can't identify why sometimes it works and sometimes it doesn't). If you want to try, this has worked before.
If you started AutoPunching with Gmail and you have some older receipts you still need to punch, manually forwarding won't work. But once you have AutoPunch up and running, you can try following these steps (i've had some luck with it):
1) Find the older receipts and put them in the trash.
2) In the trash, mark them us unread.
3) In the trash, choose the option to move them back to the inbox.
When they go back into the Inbox, your forwarding filter will work as if it's a new message and should forward it to us correctly so we can punch the order.