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.

Reply via email to