Thanks for the reply, Jim. The only reason I was using that machine servername was the way I had my external DNS setup. TCH's servers were the most preferred MX hosts, but in the event it fell through to my backup MX, I needed an external host to forward messages to. Unfortunately that caused a mail loop when the domains were left the same (ie: yourTCHaccount@yourTCHdomain.com). Using the myTCHaccount@server94.totalchoicehosting.com solved that problem until it 'broke' or was reconfigured.
No worries, I've managed to implement a cleaner solution anyway for now. But, if I wanted to, can myTCHaccount@serverXX.tchmachines.com be used as another method of reaching my hosting account?
Thanks!