On Tue, Sep 02, 2014 at 01:21:47PM -0400, Wietse Venema wrote:
> Viktor Dukhovni:
> >
> > In the RFC editor queue as of 2014-08-29:
> >
> > https://datatracker.ietf.org/doc/draft-ietf-appsawg-nullmx/
>
> Hmm. This text says:
>
> When a submission or SMTP relay server rejects an envelope recipient
> due to a domain's null MX record, it SHOULD use a 521 reply
> code [...]
>
> Both 221 and 421 are sent at the end of an SMTP session. Postfix
> uses 521 for the same purpose: is is like 421 except that the client
> should not retry.
>
> Maybe the draft can be modified.
It is rather late in the process, with the draft in the RFC Editor's
queue the only chance to modify it is I think AUTH48, and the nature
of the allowed changes is limited.
Yes, the recipient and sender basic response codes are backwards,
this is a bug. It should/could be 521 for rejecting a nullmx sender
domain, but definitely not for a nullmx recipient domain.
--
Viktor.
