Hi. I am in the process of replacing my exchange 2000 server with exchange 2003. I followed the step by step guide "Migrating exchange 2000 to Exchange 2003 using new hardware". I now have the old 2000 server and the new 2003 server running, seeming without issue. My problem is that I cannot send messages from clients connected to the 2003 server to clients connected to the 2000 server. There is no issue sending messages within the 2003 server, within the 2000 server and from the 2000 server to the 2003 server. I can even send and receive external messages with the new server. Any help would be greatly appreciated. Cheers, David.