Subject: Re: IESG intends to publish conflicting RfCs causing loss of legit e-mails

From: Tony Finch <[email-masked]>
Date: Tue, 14 Jun 2005 19:07:35 +0100

Bill Sommerfeld <[email-masked]> wrote:
>
> I have not been able to find a concise description of exactly what havoc
> will ensue

wayne <[email-masked]> wrote:
>
> Also, one of the open issues with SPF is the ability to deal with
> forwarded email.  One of the most promising solutions to this problem
> will break if the MARID proposal is used.  See section 9.3.1.2:
> http://www.schlitt.net/spf/spf_classic/draft-schlitt-spf-classic-02.html#forwarding

To expand on what wayne said, the hack described in 9.3.1.2 allows SPF
and systems like BATV (http://mipassoc.org/batv/) to work very nicely
together. The problem occurs if the SPF record is interpreted according
to Sender-ID and the PRA is used instead of the return path. Techniques
like BATV distinguish between the return path and other sender-related
email addresses, such that those addresses in the message header used by
Sender-ID do not include the crypto token. Therefore the stunt DNS server
that handles the SPF lookups will cause Sender-ID implementations to
reject the message because they will not include the crypto token in their
queries.

Tony.
-- 
f.a.n.finch  <[email-masked]>  http://dotat.at/
BISCAY: WEST 5 OR 6 BECOMING VARIABLE 3 OR 4. SHOWERS AT FIRST. MODERATE OR
GOOD.

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