Exchange server with 3 domains

Hello all, is there a way with a exchange server that handles 3 domain accounts to set up out look to send and recieve from all three domains?? I have shared my inboxes and calendars and that just doesn't work well enough I would like to have it like if I set up a exchange acount and a pop 3 account outlook allow you to see both accounts and allowes you to send mail from either account with out that much work any suggestions????