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Re: [dmarc-ietf] Ticket #1 - SPF alignment

Jim Fenton <fenton@bluepopcorn.net> Sat, 30 January 2021 21:39 UTC

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From: Jim Fenton <fenton@bluepopcorn.net>
To: John Levine <johnl@taugh.com>
Cc: dmarc@ietf.org
Date: Sat, 30 Jan 2021 13:39:56 -0800
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Subject: Re: [dmarc-ietf] Ticket #1 - SPF alignment
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On 30 Jan 2021, at 13:23, John Levine wrote:

> In article <CF0B307A-C83A-4FF9-BC03-9DE28362DF3A@bluepopcorn.net> you 
> write:
>> The issue isn’t the existing use of HELO names, it’s how they 
>> could
>> be (mis-)used. The fact that a message sender can put anything there
>> makes HELO basically meaningless.
>
> This is DMARC -- the HELO domain has to match the header From: and 
> there
> has to be an SPF record that validates it.

True, but only if the MAIL FROM address is null and there isn’t a 
valid aligned DKIM signature.

> The most plausible case is that it's a bounce messsage
>
>  From: MAILER-DAEMON@mta27.foo.bar.example.com
>
> the MAIL FROM is null, HELO is mta27.foo.bar.example.com, and the SPF
> record for mta27.foo.bar.com says that IP is OK.

So in this case, why involve the HELO at all? One could just check the 
SPF record of the header From: that it’s trying to align with. Except 
that’s probably SenderID, not SPF.

-Jim

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