Paul Borokhov writes:
Question: Is there any reason that clients should *not* punycode *all* addresses when sending messages and convert them back to proper Unicode at display time?
Even if this were a good idea (I think it's not) it's impractical by now. There are about 70,000 SMTP servers that advertise support for SMTPUTF8 now, and another million-plus that has the necessary code, but disabled in the configuration. Few of them use it, but they are deployed now and at god knows how many different sites. The majority of those are implemented according to the RFCs. None of the RFCs say "MTAs MUST regard punycode and UTF8 as equal for resolving aliases", "MUST regard punycode and UTF8 as equal for looking up local users" etc. Changing the definition of address equality/identity is sure to lead to interop pains. Arnt