According to these pages:

http://yahoomail.tumblr.com/post/82426900353/yahoo-dmarc-policy-change-what-should-senders-do

They say this:

"*If you are a mailing list owner, what should you do?*

Mailing lists are a special case of sending mail on behalf of individuals.
The most common option is to use the mailing list’s address instead of the
sender’s on the From: line. This will change the reply behavior. Some
mailing lists also choose to act as pure forwarders and resend the mail
without breaking DKIM signatures. As of this publication, no common mailing
list packages provide straightforward configuration options that produce
DMARC compatibility, although Mailman has relevant features starting in
2.1.16. If you are a developer of mailing list software and would like help
adding features to allow participants from domains with DMARC p=reject,
please contact us at dmarc-help at yahoo-inc.com.

More information about the DMARC specification and implementation advice is
available at http://dmarc.org/"

It seems like they believe Mailman has started to support the requirement
capabilities in Mailman 2.1.16, and it is theoretically possible to support
the required capabilities. I guess it's a bit premature for them to make
the leap without being sure... but I do have sympathy for the idea that
somebody has to be first, and nothing will kick the various mailing list
software providers into adding support for DKIM signatures then breaking
them for a major source of emails...

I think my suggestion would be to make sure Slony is hosted by Mailman
2.1.16 or later, that some minimal effort is put into enabling the
capability they describe ("Not breaking DKIM signatures...") and if it's
not good enough, then so be it. Yahoo users can complain to their provider?
At least you tried, so it's not your fault?



On Wed, Apr 16, 2014 at 3:07 PM, Andrew Sullivan <ajs at crankycanuck.ca>wrote:

> On Wed, Apr 16, 2014 at 10:34:23AM -0400, Jan Wieck wrote:
> > addresses possible again. I am in favor of following exactly the
> > same route and block all mail from @yahoo.com (and other DMARC
> > participating ISPs) on our lists.
>
> Just to be clear, it's not "DMARC participating", but a particular
> profile of DMARC.  This particular DMARC setting is well-known to be
> inappropriate for this kind of mail use.  That doesn't mean that all
> uses of DMARC would have the same results.  Google, for instance, is a
> big proponent and user of DMARC, and yet they have managed not to
> break mailing lists.
>
> A
> --
> Andrew Sullivan
> ajs at crankycanuck.ca
> _______________________________________________
> Slony1-general mailing list
> Slony1-general at lists.slony.info
> http://lists.slony.info/mailman/listinfo/slony1-general
>



-- 
Mark Mielke <mark.mielke at gmail.com>
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