Try to become more DMARC-complient on the mailing lists to improve deliverability, particularly given Yahoo and AOL recently switched to a policy p=reject, preventing these users from sending emails to the mailing lists.
This bug is partly wontfix since this is linked to an upstream Mailman for a proper resolution, but could be partly mitigated by changing some configuration parameters, although there is no proper solution. I open this bug partly to isolate this mailing lists issue from other DMARC-related bugs (56414, 59731, 64795), and properly tracking the issue.
1/ http://www.spamresource.com/2014/04/run-email-discussion-list-heres-how-to.html is a way to mitigate the issue, although the main point is to change the From: header to a fixed address like firstname.lastname@example.org (quite disruptive for all users).
2/ http://www.ietf.org/mail-archive/web/ietf/current/msg87176.html proposes to rewrite Yahoo (+AOL) sending addresses from email@example.com to firstname.lastname@example.org to bypass DMARC.