Hi All I want to deploy EX 2007 in our org. which is EX 2003 environment. Is it a requirement to deploy the Edge transport role in EX 2007 and EX 2003 co-existence? Is it possible to just deploy EX 2007 Mailbox server role, Hub Transport and Client Access in one box and have the routing and and filtering done from the EX 2003 Front End server for outgoing and incoming email?

It's not necessary to deploy Edge Server Role in your environment. Just deploy CAS,HTS and mailbox Server role in exchange 2003 ORG, andkeep using EX03 FE send and receive email~