diff --git a/roles/mail/templates/mailman/mm_cfg.py.j2 b/roles/mail/templates/mailman/mm_cfg.py.j2
index 1c16b47..3b855e3 100644
--- a/roles/mail/templates/mailman/mm_cfg.py.j2
+++ b/roles/mail/templates/mailman/mm_cfg.py.j2
@@ -108,6 +108,8 @@ DEB_LISTMASTER = 'postmaster@{{ mail_domain }}'
 
 # Remove, rename and preserve DKIM headers
 REMOVE_DKIM_HEADERS = 3
+# Munge From for DMARC
+DEFAULT_DMARC_MODERATION_ACTION = 1
 
 # Note - if you're looking for something that is imported from mm_cfg, but you
 # didn't find it above, it's probably in /usr/lib/mailman/Mailman/Defaults.py.