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Re: [spf-discuss] Re: GMAIL mis-usage of SPF?

2005-11-17 18:37:38

----- Original Message -----
From: "Frank Ellermann" <nobody(_at_)xyzzy(_dot_)claranet(_dot_)de>


Hector Santos wrote:

Sorry, Frank, call me what you like.

LOL, better not, and I wouldn't try to report "best guess"
in Received-SPF.  But I've no problem if others do this as
long as it clearly says _guess_

So now your mail filter needs to look for something that is not part of the
SPF standard?

    Received-SPF: None
    Received-SPF: Pass
    Received-SPF: Fail
    Received-SPF: Softfail
    Received-SPF: Neutral
    Received-SPF: TempError
    Received-SPF: PermError

The SPF specs are:

   result           = "Pass" / "Fail" / "SoftFail" / "Neutral" /
                      "None" / "TempError" / "PermError"

There are not consideration for "GUESS"

The above are the only tags that the parser will look for per SPF
specification.

Why not just do it right?

    Received-SPF: PASS-Best-Guess
    Received-SPF: PASS-Maybe
    Received-SPF: PASS-No-Fail-I-Giveup
    Received-SPF: PASS-SnakeEye-Craps
    Received-SPF: PASS-GAS

Of course it's not specified, SPF is about sender policies,
not about receiver policies.

Exactly, so if there is NO SPF policy, the only real result per
specification is:

    Received-SPF: None

But from a receiver's POV it can make sense to use
such "best guess" approaches.

And a bear does it business in a forest, sure.  Of course, it can anything
it like, but if it doesn't follow the SPF specs and adds stuff that isn't
PART of the specs, then it really isn't compliant and it makes the matter
worst for everyone down the pike. It screws up 3rd party Mail Filter authors
because when they parse for PASS, they didn't EXPECT it to mean it was
anything but a a SPF NONE condition and they didn't expect PASS may come
with a "BEST GUESS"

This is telling implementations they need to look for the word "GUESS"
because the PASS was really a lie. If you want implementatios to follow
this, then add it to the spec, and do it right:

    Received-SPF: None (gmail.com: CLIENT MATCH
                  HELO domain abusecore.charter.net
                  matches IP 209.225.29.51)

But for GMAIL.COM to say instead:

    Received-SPF: pass (gmail.com: best guess
        record for domain of root(_at_)abusecore(_dot_)charter(_dot_)net
        designates 209.225.29.51 as permitted sender)

is completely wrong and since there is no standard, others may follow what
GMAIL.COM did.

The trurh was: It was not a pass and the root domain DID NOT designate the
address as a permitted sender because there was NO sender policy.

Come on folks.  Stuff like this doesn't help SPF. It hurts SPFs.

I agree with Scott. if this perl library is suppose to be a standard example
of an SPF implementation then a) either it needs to remove this feature, or
b) correct it to say something lie above with Received-SPF: None, and c)
more importantly, add it to the specifications because this is something
anyone following the specs will not know about.

--
Hector Santos, Santronics Software, Inc.
http://www.santronics.com





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