diff --git a/roles/postfix-mailman3/templates/postfix/main.cf.j2 b/roles/postfix-mailman3/templates/postfix/main.cf.j2
index 5c8cb165..67a57108 100644
--- a/roles/postfix-mailman3/templates/postfix/main.cf.j2
+++ b/roles/postfix-mailman3/templates/postfix/main.cf.j2
@@ -23,7 +23,7 @@ smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
 smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
 
 # OpenDKIM
-milter_protocol = 2
+milter_protocol = 6
 milter_default_action = accept
 smtpd_milters = inet:localhost:12301
 non_smtpd_milters = inet:localhost:12301