Rewrite 'from' header to enable forwarding to overcome dmarc restrictions?

[Jerry Benton]

Trever,

I use Postfix rather than sendmail, but it sounds like this is an issue
that can be handled what postfix calls canonical maps. However, I cannot
recall if the headers are correctly updated, but I think they are. I do not
recall seeing problems with DKIM or SPF when used with canonical maps, but
I could be wrong. It happens all the time. Just ask my wife.




On Wed, May 7, 2014 at 5:35 AM, Mark Sapiro <mark at msapiro.net> wrote:

> On 05/06/2014 08:03 PM, Furnish, Trever G wrote:
> > Hi, Mark.  It's not breaking dkim, it's violating the receiver's
> implementation of SPF, which appears to be looking not just at the envelope
> header, but also at message headers -- I wonder whether this means they
> have actually implemented SenderID rather than SPF.
>
>
> If the message is DKIM signed by the domain of the address in From:, it
> should pass DMARC as long as the signature is valid.
>
> The tests are:
> Is there a valid DKIM signature with a d= domain that "aligns" (a DMARC
> technical term) with the domain of the From: address
>
> or
>
> Does the server pass SPF and does the domain of the envelope sender (the
> SPF domain) "align" with that of the From: header.
>
> Forwarding will break SPF alignment, but if there is an original DKIM
> sig and it is valid, the message should still pass DMARC.
>
> See the spec at
> <https://datatracker.ietf.org/doc/draft-kucherawy-dmarc-base/> and lots
> of descriptive info at <http://www.dmarc.org/>
>
> --
> Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
> San Francisco Bay Area, California    better use your sense - B. Dylan
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-- 

--
Jerry Benton
Mailborder Systems
www.mailborder.com
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