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Re: [Ietf-dkim] Question about lone CR / LF

John R Levine <johnl@taugh.com> Fri, 02 February 2024 03:32 UTC

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From: John R Levine <johnl@taugh.com>
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Subject: Re: [Ietf-dkim] Question about lone CR / LF
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>> Layering is a fine principle, but it's not how DKIM has ever worked in 
>> practice.  Two weeks ago we had a long discussion about oversigning, so 
>> DKIM validators can catch messages with multiple From: or Subject: headers 
>> which have never been valid in any version of 822/2822/5322 but show up 
>> anyway.
>
> Please explain how you think DKIM violates layering.

What I said in my previous message, people use oversigning to catch 5322 
header violations.

>> For the specific issue of bare CR or LF, I was reminded on another list 
>> that there is a trendy attack called SMTP smuggling which depends on mail 
>> software inconsistently accepting bare CR or LF, and mail providers are 
>> busy patching to fix it.
>
> That has nothing to do with DKIM, of course.

Opinions differ.

Regards,
John Levine, johnl@taugh.com, Taughannock Networks, Trumansburg NY
Please consider the environment before reading this e-mail. https://jl.ly

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