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

[Mark]

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 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?)

thanks
Mark.