Question : 4.1.8 Domain of sender address <[email protected]> does not resolve

I am doing a POC of Exchange 2003 to 2007 migration in a test lab. The external name is registered on the Internet. The Exchange 2003 Internet send connector was configured to point to the companies ironport device as a smart host for outbound mail. This worked just fine and mail was sending outbound just fine. We then introduced Exchange 2007 and it routed just fine out this connector. Then we moved all the mailboxes and decommissioned Exchange 2003, which made this connector not funtion any longer becuase it was a Exchange 2003 connector. We removed the the legacy send connector and created a new Exchange 2007 send connector. I pointed this send connector to the same smart host as the Exchange 2003 send connector was using. We configured IronPort to allow both HUBCAS servers to send mail to the IronPort devices. Both HUBCAS servers are set as source servers on the new send connector.

Now when I try sending Internet bound email, The messages are stuck in the queue with this 4.1.8 Domain of sender address does not resolve error. I didnt have to add any fqdn name to the Exchange 2003 send connector to get that to work. I am wondering why it will not function in Exchange 2007.

Answer : 4.1.8 Domain of sender address <[email protected]> does not resolve

You said you set the ironport devices to be allowed to accept mail from the hubcas servers, do you have to allow relay?