Re: [Asrg] misconception in SPF

Dotzero <> Tue, 11 December 2012 15:29 UTC

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Date: Tue, 11 Dec 2012 10:29:46 -0500
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Subject: Re: [Asrg] misconception in SPF
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On Tue, Dec 11, 2012 at 9:46 AM, John Levine <> wrote:
>>No. I know some do, but I think it's a minority. (Among commercial spam-filters used mainly
>>by corporations, that is. It could be that some of the larger ISPs block SPF fails outright,
>>which would skew the picture.)
> No ISP I know does that.  The false positive rate is much too high,
> since publication of a -all record is highly correlated with
> assertions that all forwarding is evil, which is of course just wrong.

I concur with John - The false positive rates, misconfigurations in
records, etc. are one of the reasons for the development of DMARC and
the buy-in by major mailbox providers (See announcement by MS
yesterday for implementing DMARC and switching from SID to

I'm not sure I agree with John that a -all record is somehow an
assertion that all forwarding is evil. I'll save that discussion for
drinks the next time I see him.