I getting the following delivery error below when sending to an outside domain. My 2007 Exchange server sends messages destined for a particular domain to a POP3 server setup in my network domain. The POP3 server is rejecting the messages because of security policies. I think something in the migration from Exchange 2000 is causing this issue. How can I stop 2007 from sending messages destined for this particular domain to the POP3 server? I don't know why the POP3 server was setup but we don't need it.
Delivery has failed to these recipients or distribution lists:
Your message wasn't delivered because of security policies. Microsoft Exchange will not try to redeliver this message for you. Please provide the following diagnostic text to your system administrator.
The following organization rejected your message: mobile.mydomain.com.
Sent by Microsoft Exchange Server 2007