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Re: [ietf-smtp] [dmarc-ietf] Fwd: RFC 7372 on Email Authentication Status Codes

2014-09-17 15:51:19
Hi,

On 09/16/14 05:08, Murray S. Kucherawy wrote:
>          URL: https://www.rfc-editor.org/rfc/rfc7372.txt
>
> This document registers code points to allow status codes to be
> returned to an email client to indicate that a message is being
> rejected or deferred specifically because of email authentication
> failures.
>
> This document updates RFC 7208, since some of the code points
> registered replace the ones recommended for use in that document.

I hope this is not off topic here:

(chair hat on)

It is. I've cc'ed and directed replies to the ietf-smtp list, where this sort of discussion belongs.

(chair hat off)

RFC 7372 proposes to use a 550 response code for reverse DNS auth
failures, see section 3.3.

Correct.

Reverse DNS checks are usually done early in the connection (like IP
blocks) in the connection establishment stage of the SMTP dialog.

RFC 5321 allows only a 554 error response there, see section 4.3.2.

You're misreading RFC 5321. Nowhere does it say that its lists of possible
responses are exhaustive. So it is perfectly permissible for RFC 7372 to
specify additional possible responses as long as they fit into the overal
theory of reply codes.

This sort of thing has been done many times.

So, shouldn't a 554 code be used here? Or does RFC 5321 need an update?

Neither. See above.

                                Ned

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