new exchange server send emails but does not receive emails

I installed new Exchange 2003 server on new Server. The same time still have old Exchange 2003
on another Server. I moved all user accounts and public folders into new Server. New Exchange works.
BUT !!!
If I shut down old Exchange , New One may send emails within domain and outside. The same time can not receive emails from outside.
If I boot back old Exchange –> can receive and send emails internal and external.
It tells me that old server acts as some kind router. I can see from Queues on old server record with new Exchange name which does the routing.
DNS records and firewall rules are checked and look correct.
I need to remove the old server from domain.
Any Idea how to fix the problem ???

Thanks in advance