Re: [spfbis] Local macros strike again, was Suggestion...

[Philip Gladstone <[e-mail]>]

There is significant value in distinguishing neutral from positive. This 
is when this signal is an input into an anti-spam system. A positive SPF 
eval will (typically) allow slightly spammier looking emails through, 
whereas a neutral would be slightly stricter.

Philip

On 1/22/2012 12:55 AM, Hector Santos wrote:
> Hi Murray,
>
> I guess it all depends on how its written, but my only concern is that
> no one should get bent out of shape about trying to implement a
> "default rule" that would apply to all. I say that from the point of
> view that REJECTION is a strong part of SPF and this best guess idea
> can only serve a purpose for "reporting," at best, for one data point:
>
>     The sender and receiver are part of the same network.
>
> If this was a fundamental concept for all, i.e. part of the spec, then
> I can see the default "rule" applying for filters and IMO, we really
> never would need SPF.
>
> But that is not an SMTP setup operational requirement, so I find no
> value in this default rule other than getting some "interesting data
> point" about the sender network setup.  The Sender/Receiver is part of
> the same network. So what?  It means nothing, at least I don't see it
> unless a NON-SPF logic is done to see if the MX is black listed or
> doesn't exist.
>
> Per SMTP, an MX is not a requirement and we use a fall back to the A
> record.  If that fails, depending on the implementation it could be
> filtered. i.e. many systems use a "NO MX/TRIED A record Once" concept
> when sending mail.
>
> --
>
>
> Murray S. Kucherawy wrote:
>>> -----Original Message-----
>>> From: [e-mail] [mailto:[e-mail]] On
>>> Behalf Of Hector Santos
>>> Sent: Wednesday, January 18, 2012 2:46 AM
>>> To: [e-mail]
>>> Subject: Re: [spfbis] Local macros strike again, was Suggestion...
>>>
>>>> AFAIK, t-online.de never published SPF records.  Some implementers
>>>> leveraged SPF built-in functions to make "best guesses" about domains
>>>> lacking SPF records.  This tactic is found in many SPF implementations
>>>> as it will be for years.
>>> Who?
>>>
>>> This must be completed isolated.
>>
>> It's not.  A Google search for "best guess SPF" comes up with
>> numerous records, and I've seen it referenced in white papers.  And I
>> know for a fact that Gmail uses it.
>>
>> The best definition I've seen is here:
>> http://www.openspf.net/FAQ/Best_guess_record
>>
>> I think part of the -bis effort should include an appendix that talks
>> about this, albeit informatively, just so that a real consensus
>> definition exists someplace.
>>
>> -MSK
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>>
>>
>

-- 
Philip Gladstone
Distinguished Engineer
Product Development
[e-mail]
Phone: +1 978-ZEN-TOAD ([phone])
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