[Dovecot] Managesieve AUTHENTICATE with IDN using UTF-8 or encode into ACE?

[Florian Zeitz]

Am 21.02.2012 16:05, schrieb Christian Rohmann:
> Hey dovecot-users,
> 
> clients that speak telnet based protocols like http, smtp usually encode
> IDN (International Domain Names) containing UTF-8 characters into ACE
> (ASCII Compatible Encoding) punycode.
> 
> I am wondering what the case was with managesieve (RFC 5804). For
> example if I was using a username like "user@äüö.example.com" with the
> AUTHENTICATE command. Would that need to be encoded into ACE or be left
> in UTF-8? Reading section "2.1. AUTHENTICATE Command" or "4. Formal
> Syntax" suggests that quoted or literal UTF-8 is correct.
>
Hy,
what you're asking for is the correct format of the simple username.
This is in fact deployment specific. There is in general no requirement
to include the domain at all. The only requirement for to fulfil is that
it must not contain any codepoints prohibited by the SASLPrep stringprep
profile.
As such both the ACE and the IDN variant are valid. Which one to choose,
or whether to use only "user" depends on local policies.
There might be some implementation specifics in dovecot/pigeonhole that
I'm not aware of though.

Regards,
Florian