I migrating from Exchange 2003 to 2010. I am trying to set my exchange 2003 server to use the Exchange 2010 server to send and receive all email. I have created the routing group connectors on the exchange 2010 server to connect to the exchange 2003 server. My exchange 2003 server can receive email internally and externally and can send email internally. But it cannot send mail externally. I am getting an NDR that says:
The following recipient(s) could not be reached:
You do not have permissionto send to this recipient. For assistance contact your system administrator
<server name> %5.7.1 smtp:550 5.5.1 Unable to relay
Can anyone point me in the right direction to resolve this?