"they're converted to punycode for submission, because that's what the server will need in order to use the address" I disagree with that. Neither the client n

"they're converted to punycode for submission, because that's what the server will need in order to use the address" I disagree with that. Neither the client nor the server need to know anything about punycode. The only time punycode is required is at the very last moment when it comes time to actually send an email to that address. Whether it's the email sending library or the mail server it's self, it doesn't matter. A user should be able to type "person@ü.example.com" into a form. I should receive "person@ü.example.com" on the server side. I should save "person@ü.example.com" to the database. I should be able to send "person@ü.example.com" back to the browser for display, and I should be able to pass "person@ü.example.com" as the To address to my mail sending library. Punycode is an implementation detail that I shouldn't need to think about.