All Chinese Domain name has to be translated to punycode for DNS server to resolve, that is to say, the translation is done at your client. I found fox mail has that function already, if you mail to a Chinese domain name, it will be automatically translated to punycode format as we can see in IronPort.
You can either choose translate it online or some tools to translate it as IronPort has nothing to do with that job.
It is easy to set an internet's root DNS server, if you want to set to some one else, choose "Use these DNS Servers" on the web GUI.