[UA-EAI] EAI Evaluation Widget

[John R. Levine]

>> punycode at punycode is certainly allowed, but the "punycode" in the local part is an ASCII local part that starts xn--..., not coded UTF-8.
>
> That’s not clear to me. I see neither any SHOULD nor any MUST that SMTP 
> servers must treat punycode in domains as they would unicode. Maybe I’ve 
> missed something?

Punycode is just ASCII text, and ASCII text is certainly valid in the 
local part of an address.  A mailbox like xn--ls8h is just as valid as 
any other.  The fact that it happens to look like an A-label is a 
concidence.

Regards,
John Levine, johnl at iecc.com, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail. https://jl.ly

PS: A few weeks ago someone reported with great fanfare that some MUAs 
have bugs that try to decode local parts that look like punycode, which 
allows some obvious phishing attacks.  But those are just bugs.