Re: [ opendkim-Bugs-3590402 ] No signature if From header is first (fwd)

From: Murray S. Kucherawy <msk_at_blackops.org>
Date: Tue, 27 Nov 2012 15:25:16 -0800 (PST)

On Tue, 27 Nov 2012, Steve Jenkins wrote:
> The FROM is in the very first line: MAIL FROM:
> Or am I not understanding the question?

MAIL FROM and RCPT TO define the message envelope, not the actual message
header or body.

A normal session would look like this:

<< 220 blah blah
>> EHLO hostname
<< 250 ok
>> MAIL FROM:<sender_at_example.com>
<< 250 ok
>> RCPT TO:<recipient_at_example.net>
<< 250 ok
>> DATA
<< 354
>> From: Mister Sender <sender_at_example.com>
>> To: Madame Recipient <recipient_at_example.net>
>> Subject: This is a test
>>
>> This is the body
>> .
<< 250 ok
>> QUIT
<< 221 bye!
<< (disconnect)

HELO, MAIL FROM and RCPT TO are envelope information, which is the stuff
that lands in Received: fields.

So the actual From: field comes after DATA. If you didn't include one,
then either opendkim signed something it shouldn't have (the absence of a
From: means it shouldn't sign the message), or postfix gave it a From:
based on the MAIL FROM, or some other kind of magic happened.

-MSK
Received on Tue Nov 27 2012 - 23:25:32 PST

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