I just realized that this would not resolve the issue because the remote MX would just redeliver it to the local server which is the final destination of the domain. I'm probably better off with a simple alias domain forward.
So while it's not worth considering how to tweak my specific configuration, I'd still be curious to know why the transport map.. [EMAIL PROTECTED] smtp:mx.myexternaldomain.com ..produces a "Relay access denied" error. Does the relay access need to be specifically allowed for that destination even though the transport is "internal" by a mapping? Ville