Aha! I'm not the only one. I've had the exact same problem but with prodigy. It's like the Cuda can resolve the A record from DNS but not the MX record or something. Nslookup looks totally normal to me.My resolution was to go under the Domains tab and hard-code the IP address for prodigy. The mail gets delivered that way but if they change their IP addresses on their end for whatever reason then I have to update the Cuda before mail will flow again