IDN Email Bug in iOS Mail

If you happen to have an email address that uses an International Domain Name (IDN), i.e. one which includes non-ASCII characters (like info@蓝天东.org), you will find that it's not possible to set up an account in iOS Mail, even when you use the Punycode/ascii version (info@xn--xhq32y7n9a.org in the case mentioned earlier). It just says the address is invalid and you cannot go further. You can,