Re: [spfbis] Should we encourage the use of SPF "soft include" for common platforms?

Alessandro Vesely <vesely@tana.it> Mon, 25 February 2019 10:24 UTC

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To: "Kurt Andersen (b)" <kboth@drkurt.com>, "dmarc@ietf.org" <dmarc@ietf.org>
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From: Alessandro Vesely <vesely@tana.it>
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Subject: Re: [spfbis] Should we encourage the use of SPF "soft include" for common platforms?
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On Sat 23/Feb/2019 19:07:31 +0100 Kurt Andersen (b) wrote:

> With the growth of huge platforms that emit mail from the same common set of
> IPs (such as GSuite, O365, or large ESPs), regular SPF "include" ends up
> granting a DMARC pass to a lot more potential authors than most organizations
> would necessarily choose to grant.


Hopefully, large organizations have a policy which enables them to drop
non-compliant users contracts.  The admin attitude.

Alternatively, they could expunge offending IP addresses from their SPF
records.  The whitelist attitude.

The rest is reputation.


> Instead of using the standard "(+)include:" approach, if domain owners used
> "?include:" as their mechanism, then that would prevent the SPF result from
> granting a DMARC PASS result when traffic is coming from one of these massively
> included platforms. It would essentially force the DMARC result to be driven
> only by the DKIM evaluation.


-1.  If DKIM were flawless, maybe...  Authentication of email messages
forwarded through various providers is already DKIM-only driven, but that
doesn't seem to improve reliability, does it?


Best
Ale
--