Re: [dmarc-ietf] Nitpicky questions about DMARC record syntax

Dave Crocker <> Wed, 16 January 2019 15:05 UTC

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To: John Levine <>,
References: <20190116005804.A0A80200CACDA9@ary.qy>
From: Dave Crocker <>
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Date: Wed, 16 Jan 2019 07:05:10 -0800
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Subject: Re: [dmarc-ietf] Nitpicky questions about DMARC record syntax
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On 1/15/2019 4:58 PM, John Levine wrote:
> I am staring at RFC 7489, and at a bunch of purported DMARC records
> (see previous message.)
> The RFC says that all records must start with "v=DMARC1".  Is it OK
> if they start with "v=dmarc1"?  It says that record is a DKIM tag-value
> list, and the DKIM ABBF defines all the characters with hex escapes
> rather than letters which tells me that it's specifically saying
> that case matters.
> How about if there's a space before the v=DMARC1?  The tag-value syntax
> allows FWS before the first tag, but 7489 says in several places

The formal specification is quite clear on both of your questions:

    Section 6.4:

    dmarc-version   = "v" *WSP "=" *WSP %x44 %x4d %x41 %x52 %x43 %x31

which means that the white space is required to be allowed and the value 
in this tag-value is case sensitive.


Dave Crocker
Brandenburg InternetWorking