[Mailman-Users] DMARC issues

[Jim Popovitch]

On Sat, Apr 12, 2014 at 6:15 PM, Peter Shute <pshute at nuw.org.au> wrote:
>> On 12 Apr 2014, at 9:28 pm, "Mark Sapiro" <mark at msapiro.net> wrote:
>>
>>>> Additional reading at <http://www.dmarc.org/faq.html#s_3>,
>>>> <http://blog.threadable.com/how-threadable-solved-the-dmarc-problem> and
>>>> <http://www.spamresource.com/2014/04/run-email-discussion-list-heres-how-to.html>
>>>> and other articles linked from those.
>>>
>>> From the threadable article:
>>> "He recommends that all list administrators immediately stop delivering to Yahoo addresses to limit damage, and encourage members to move to a more friendly provider."
>>>
>>> How would not delivering to yahoo addresses help? I thought the problem was with delivering yahoo email to others.
>>
>>
>> See Jim P's post in this thread at
>> <https://mail.python.org/pipermail/mailman-users/2014-April/076383.html>
>> and the branch linked therefrom, although you probably don't have the
>> access required to install it.
>>
>> Jim P's approach is to reject any post From: a domain with a DMARC
>> policy of reject.
>>
>> To accept a post and then not deliver it to some because you know it
>> won't be accepted is arguably wrong, and also, you can't know except by
>> experience which recipient domains will reject the post for DMARC
>> policy. I've seen the following:
>
> But note that the part of the threadable article I quoted talks about not *delivering* to yahoo addresses. I would thought that shouldn't be a problem.

The recent yahoo change means that you (as a mailinglist operator)
will have difficulties (and possibly eventually face blacklisting) by
delivering, via your list, email that originates from a yahoo.com (and
a few other) email address.  Assuming you are doing SPF/DKIM/etc, you
should have no problems delivering non-yahoo domain emails to yahoo.

-Jim P.