[dmarc-discuss] How does *this* mailing list interact with dmarc?

Elizabeth Zwicky zwicky at yahoo-inc.com
Wed Jun 20 10:29:21 PDT 2012


Don't use quarantine or reject policies on domains that contain real users; use them on transactional domains.
Mailing lists and forwarding  are both heavily used by real people and will break DMARC.

	Elizabeth

On Jun 20, 2012, at 6:20 AM, Steven Chamberlain wrote:

> Hi,
> 
> When I send this mail to the list, I would expect it to be forwarded to
> its subscribers keeping the RFC5322.From address of steven at pyro.eu.org
> 
> The dmarc.org domain has an SPF record that should authenticate the
> RFC5321.MailFrom of forwarded mails, but this will not be in alignment
> with RFC5322.From as per DMARC 4.2.2. and so is not considered.
> 
> From the list archives it appears there would be some list information
> and unsubscribe instructions appended to the message body, which would
> cause my DKIM signature not to verify.  Even if the list would apply
> some DKIM signature of its own, it cannot do so for the RFC5322.From
> domain as required by DMARC 4.2.1.
> 
> I believe this makes a DMARC failure result inevitable.  In my first few
> days of trying DMARC this has been quite apparent from my mails to
> @lists.debian.org and @freebsd.org triggering failure reports.
> 
> Some recipients like Google Mail recognise those lists and use the
> mailing_list policy override.  But this is not the default behaviour of
> DMARC and so most other mail receivers who implement it, report a failure.
> 
> With many DMARC implementors probably subscribed to this list, I expect
> to be receiving some new failure reports shortly :)
> 
> Regards,
> -- 
> Steven Chamberlain
> steven at pyro.eu.org
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