On 2022-09-22, Kai Bojens via Exim-users <exim-users@???> wrote: > Hello there,
> I have a new server which now has SMTPUTF8 enabled. I'm not sure why but
> since then at least one Outlook client decided to stop using the IDN
> form (xn--dmin-moa0i.example) and now tries to authenticate with the
> UTF-8 domain. Researching this problem has led me to some questions:
>
> 1. How does exim handle UTF-8 in authentication data?
Authentication credentials have been 8-bit since forever, exim is 8-bit
clean so, if a client offers an 8 bit credential (username, password, etc)
exim will pass that on to the lookup or whatever is being used to
check the credentials.
> 2. How does exim handle the logging of such information? I searched the
> logfile and noticed that the authentication information is logged with
> UTF-8 in octal:
>
> (set_id=xyz@XXX\303\266nX\303\244XXX.xyz)
These would be an escaped version of the bytes offered in the
credential. there is no enforcement that the credential is valid UTF8.
