Arnt Gulbrandsen:
> On Wednesday, June 4, 2014 6:45:40 PM CEST, Wietse Venema wrote:
> > You are missing the point. The internal SMTP client does not
> > look up the recipient MX host. It just gives the mail to the
> > perimeter gateway.
> >
> > Therefore, a non-EAI internal SMTP client can send an email reply
> > to an EAI sender.
>
> I am not missing the point.
>
> Compliant SMTP servers only accept mail to/from EAI addresses if the SMTP
> client uses the SMTPUTF8 form of the MAIL FROM command. The SMTP client, in
> turn, only uses that form if the origin too used it.
Postfix has accepted 8-bit headers and localparts forever, and that
will not change. The mission of Postfix is to deliver mail, to force
everyone else into compliance with some newfangled RFC.
> > Thus an EAI domain name may show up as xn--mumble in HELO commands.
>
> Yes. I think it's a bad idea to do that. The chance that some SMTP server's
> gethostbyname() will return the UTF8 form and the SMTP server then complain
> about EHLO/PTR mismatch is too great. But it can happen.
I'll read the RFCs carefully and see where it allows UTF8 in SMTP
command parameters and replies.
However even without reading those RFCs it is clear that UTF8 cannot
be used in 220 server greetings or in EHLO commands or replies,
because at that time the server/client have not agreed to use UTF8.
Thus, myhostname (or equivalent) must be ASCII, as it always must
have been. There is no need to use valid_mail_domain() in
reject_non_fqdn_hostname etc.
Wietse
