[UA-EAI] A radical idea for compatibility

[John R. Levine]

> 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?

Yes.

For one thing, it would break mail to the majority of mail users who use 
ASCII mail clients.  For another, the local parts of mail addresses are 
not always convertible to punycode, or if they are, there is a 
non-reversible canonicalization step so if you undo the punycode, you'll 
end up with the wrong local part and it won't be deliverable.

R's.
John

PS: It probably isn't a big surprise that this isn't the first time this 
suggestion has come up.