(In reply to Seb35 from comment #0)

This bug is partly wontfix since this is linked to an upstream Mailman for a
proper resolution

Can you link or file it (on launchpad)?

Apart http://dmarc.org/faq.html#s_3 which is only theoretical, I found this announcement of some support for DMARC in Mailman 2.1.16 and 2.1.18 (released April 18, 2014): http://wiki.list.org/display/DEV/DMARC

If I understand correctly, the introduced config parameter from_is_list is now on a per-list basis; this one rewrite the From: header (RFC 5322) with "Sender via the list wikitech-l" <wikitech-l@lists.wikimedia.org>, or could wrap the message as a sub-part in a MIME message.

Reply-To is unaffected, which is good (we use reply_goes_to_list). https://bugs.launchpad.net/mailman/+bug/1313010

Probably better wait for https://bugs.launchpad.net/mailman/+bug/1315970 at least.

I think we'll wait for upstream here, or rather on bug 64547 (Mailman 3).
Hence setting low priority.

This is fixed in Mailman 2.1.18, see the release announcement:

The from_is_list feature introduced in 2.1.16 is now unconditionally available to list owners. There is also, a new Privacy options -> Sender filters -> dmarc_moderation_action feature which applies to list messages where the From: address is in a domain which publishes a DMARC policy of reject or possibly quarantine. This is a list setting with values of Accept, Wrap Message, Munge From, Reject or Discard. There is a new DEFAULT_DMARC_MODERATION_ACTION configuration setting to set the default for this, and the list admin UI is not able to set an action which is 'less' than the default. The prior ALLOW_FROM_IS_LIST setting has been removed and is effectively always Yes. There is a new dmarc_quarantine_moderation_action list setting with default set by a new DEFAULT_DMARC_QUARANTINE_MODERATION_ACTION configuration setting which in turn defaults to Yes. The list setting can be set to No to exclude domains with DMARC policy of quarantine from dmarc_moderation_action.

dmarc_moderation_action and from_is_list interact in the following way. If the message is From: a domain to which dmarc_moderation_action applies and if dmarc_moderation_action is other than Accept, dmarc_moderation_action applies to that message. Otherwise the from_is_list action applies.

particularly given Yahoo and AOL recently switched to a policy p=reject, preventing these users from sending emails to the mailing lists.

They can still send emails, though not everyone on the list will receive them. I use Outlook.com for email and did not receive a recent message to wikitech-l, which came from a yahoo.com address. Apparently some other subscribers did, else there would have been no reply at all.

In T66818#846359, @lfaraone wrote:

This is fixed in Mailman 2.1.18

We are now on 2.1.18 since today. :)

We should see a decrease in bounces, right? But where are the stats now? :)

@JohnLewis: What should we be tweaking? We're still seeing problems on various ArbCom/functionaries lists.

In T66818#1905719, @lfaraone wrote:

What should we be tweaking? We're still seeing problems on various ArbCom/functionaries lists.

John is no longer active, I'll remove his assignee here, @Dzahn may know more about some options.

Fun: https://lists.wikimedia.org/pipermail/wikimedia-l/2016-February/082814.html

In T66818#1905720, @Jalexander wrote:

John is no longer active, I'll remove his assignee here, @Dzahn may know more about some options.

No, sorry, i don't know more about this.