Re: [ietf-smtp] RFC 8601, clarification needed

[John Levine <[e-mail]>]

It appears that David Bürgin <[e-mail]> said:
>1)
>
>Authentication-Results: mail.example.org; spf=pass smtp.mailfrom=example.com
>Authentication-Results: mail.example.org; spf=pass smtp.helo=mail.example.com

That is wrong.  One A-R per pass through the MTA, please.


>Authentication-Results: mail.example.org;
>  spf=pass smtp.helo=mail.example.com;
>  spf=pass smtp.mailfrom=example.com

You can do that if you want.

>A subsequent component could then use these results as input to some
>spam score, for example.

You could, although in practice the HELO check doesn't tell you anything useful
except when it's used as a fallback due to a null MAIL FROM.  The useful HELO
check is to see if it exists at all, with a nonexistent one being a close to 100%
accurate spam signal.  But if it doesn't exist, there is no SPF record so SPF
tells you nothing.

R's,
John