Hi, > I suspect that more configuration is required on the Exchange server > side...but what? Does anyone know? I think I may have to use the > Recipient Policy to add the new domain...is this correct? Consider what happens if you do nothing at your Exchange server. The DNS MX record merrily sends the @def.com emails to your Exchange server. The Exchange server correctly says: "huh!? I don't know nuttin' 'bout no @def.com, reject!". So yes, you need to do something at the Exchange server. You need to configure Recipient Policies and add the appropriate @def.com SMTP email address to each user that needs to receive it. Even if your DNS server resides on the same server as the Exchange Server and is an "integrated Microsoft DNS Server", there is no "automatically transferred knowledge" about the @def.com from the DNS server to Exchange Server, you have to configure both. Other clean and low cost solutions also exist but they require that you have access to a Linux mail server or a hosting company that provides one - contact me off-line if you need. Mike