We have a customer who is now using our cloud email service who has a 3300 ICP. We set it up to forward to our mail relay to get to our cloud system. The mail relay is denying the message because it has an invalid domain name. It is getting to the mail relay with the internal IP address of the system as the domain name ( @10.9.0.10). While that is a valid format according to the RFC, our relay is pretty locked down and will not allow an IP address as a domain name. Especially a private IP address.
Thanks in advance!