I'm in the process of migrating our Exchange to 2K3. I first built a new 2K3 server in same org/admin group/domain as our 2K server. All looked good until I moved my mailbox to the 2K3 server. Mail bound for that mailbox, as well as NEWSERVER-IS@DOMAIN.SUFFIX, just sat in a queue with the FQDN of the 2K3 server. So, I uninstalled that server and completely rebuilt it as a 2K server. All in all I get the same thing. I have verified that port 25 is open for both servers. Also, I'm seeing event id 4000 warnings in the logs. PLEASE SOMEBODY HELP!!!