[Mailman-Users] Assistance with altering reply-to behaviours and DMARC

Mark Sapiro mark at msapiro.net
Sun Aug 30 02:47:19 CEST 2015

On 08/27/2015 01:58 AM, Mark wrote:
> Hi,
> First, apologies if this has been discussed before.  I run a number of
> mailman lists on a Centos 6 platform and mailman 2.1.12-25. This version
> was updated in July as follows:
> https://rhn.redhat.com/errata/RHSA-2015-1417.html and included fixes for
> a number of DMARC issues.  Including "... With this update, domains with
> a "reject" DMARC policy are recognized correctly.."
> Normally the lists we use are configured with reply_goes_to_list and
> anonymous_list is off.  We have done some testing, and we have not been
> able to identify settings that will retain reply_goes_to_list
> functionality  and turn on DMARC Mung.
> Generally what happens is that the first message is successfully sent to
> a yahoo.com address and this user can reply to the message as normal. 
> However, mailman adds the original sender to the reply-to meaning that
> when another user replies to this message reply_goes_to_list doesn't work.

It should reply to both the list and the original poster and any other
addresses in Reply-To; If it isn't, the replying MUA is at fault. RFC
5322, sec 3.6.2 says in part "When the "Reply-To:" field is present, it
indicates the address(es) to which the author of the message suggests
that replies be sent."

That said however, this is a bug. For a list with reply_goes_to_list =
This list, The original poster's address should be added to Cc:, not
Reply-To:. See <https://bugs.launchpad.net/mailman/+bug/1407098>, fixed
in Mailman 2.1.19.

If RedHat is going to backport these mitigatations into their package,
they should keep up.

> It seemed to me that a small modification to CookHeaders.py could
> prevent the adding of the original sender email to "Reply-To"
>         # We also need to put the old From: in Reply-To: in all cases.
>         if o_from:
>             add(o_from)
>         # Set Reply-To: header to point back to this list.  Add this last
> seemed like a good place to look, but before I try to debug commenting
> out this didn't prevent the addition of the original sender to Reply-To
> I would ask for some advice !!
> any assistance would be very helpful!!   (it maybe that changing the
> order of addresses in the Reply-To field would all reply_goes_to_list
> would work?)

See the fix at
If you apply this, you need both the CookHeaders.py patch and the
WrapMessage.py patch.

Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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