diff --git a/playbooks/roles/mailman3/templates/mailman-extra.cfg.j2 b/playbooks/roles/mailman3/templates/mailman-extra.cfg.j2
index 1ef0a56256..5882adcd95 100644
--- a/playbooks/roles/mailman3/templates/mailman-extra.cfg.j2
+++ b/playbooks/roles/mailman3/templates/mailman-extra.cfg.j2
@@ -4,3 +4,10 @@
 # bounce from a list owner), will be sent to this address.  It should point to
 # a human.
 site_owner: "root@{{ ansible_fqdn }}"
+
+# The outgoing runner is what is responsible for sending email. By default
+# there is only one instance of this runner. We have seen some emails get
+# queued up for 5-10 minutes in lists with larger membership. Increase this
+# value to 4 to improve outgoing mail throughput.
+[runner.out]
+instances: 4