I've searched the other solutions to this problem, but none seemed relevant.
Our email is hosted as POP accounts, and we're using eXchange POP3 (a very fine product, BTW) to collect mail from the POP accounts and deliver them to the Exchange server (no lectures please on how this is not cool...there are a number of reasons why we're doing this).
We're switching our domain name, but haven't completed changes yet. In anticipation of the switch, I added to the Generation Rules under the default Recipient Policies the new domain, newdomain.com, but left it unchecked and kept olddomain.com checked.
When I try to send email to any account @newdomain.com, I get "A configuration error in the e-mail system caused the message to bounce between two servers or to be forwarded between two recipients. Contact your administrator." I've ramped up the Diagnostics Logging to maximum and looked each send up in the Message Tracking Centre, but the message never leaves the system. The last two events are "Message Routed and Queued for Delivery," and then the NDR is generated.
Thinking it might be Exchange looking internally for newdomain.com, I removed the entry from the Generation Rules, and applied the policy, but the error persists. I then flushed the global and Exchange server DNS caches, just in case, but no luck.
Where can I look to purge newdomain.com from the Exchange server's brain, if indeed that is the issue.
Note that mail from other servers, e.g., hotmail.com, delivers successfully to newdomain.com.
Also, although olddomain.com is similarly hosted as a series of POP accounts which eXchange POP3 collects, we have never experienced this error running Exchange in this configuration.
All zone information for newdomain.com points to the external host, i.e., nothing points to the Exchange server. In fact, our internal domain has nothing to do with either olddomain.com or newdomain.com.