diff --git a/inventory/service/group_vars/mailman3.yaml b/inventory/service/group_vars/mailman3.yaml
index d941d046d6..9d7bcca469 100644
--- a/inventory/service/group_vars/mailman3.yaml
+++ b/inventory/service/group_vars/mailman3.yaml
@@ -25,8 +25,9 @@ borg_backup_excludes_extra:
 exim_queue_interval: '1m'
 exim_queue_run_max: '50'
 exim_smtp_accept_max: '100'
+exim_smtp_accept_max_per_host: '10'
 # This should be set to more than mailman's mta.max_recipients value.
-exim_smtp_accept_max_per_host: '50'
+exim_smtp_accept_queue_per_connection: '50'
 exim_routers:
   - mailman_verp_router: |
       {% raw -%}
diff --git a/playbooks/roles/base/exim/README.rst b/playbooks/roles/base/exim/README.rst
index 2b6e7e4081..a2685f01b2 100644
--- a/playbooks/roles/base/exim/README.rst
+++ b/playbooks/roles/base/exim/README.rst
@@ -52,3 +52,11 @@ Installs and configures the exim mail server
    code 421. The option’s default value imposes no limit. If this option is
    set greater than zero, it is required that
    :zuul:rolevar:`exim.exim_smtp_accept_max` be non-zero.
+
+.. zuul:rolevar:: exim_smtp_accept_queue_per_connection
+   :default: null
+
+   The maximum number of delivery processes Exim will start for incoming SMTP
+   calls before it shunts them to periodic queue processing instead. If
+   the value is set to zero, no limit is applied. If this option is not set,
+   Exim will implicitly apply a default value of 10.
diff --git a/playbooks/roles/base/exim/templates/exim4.conf.j2 b/playbooks/roles/base/exim/templates/exim4.conf.j2
index 55d2d5a480..a19a3b7a7c 100644
--- a/playbooks/roles/base/exim/templates/exim4.conf.j2
+++ b/playbooks/roles/base/exim/templates/exim4.conf.j2
@@ -334,6 +334,11 @@ smtp_accept_max = {{ exim_smtp_accept_max }}
 smtp_accept_max_per_host = {{ exim_smtp_accept_max_per_host }}
 {% endif %}
 
+{% if exim_smtp_accept_queue_per_connection is defined %}
+# threshold for immediate delivery processing
+smtp_accept_queue_per_connection = {{ exim_smtp_accept_queue_per_connection }}
+{% endif %}
+
 ######################################################################
 #                       ACL CONFIGURATION                            #
 #         Specifies access control lists for incoming SMTP mail      #
diff --git a/playbooks/roles/mailman3/templates/mailman-extra.cfg.j2 b/playbooks/roles/mailman3/templates/mailman-extra.cfg.j2
index f9cf5bbccf..b3d8c0bd3b 100644
--- a/playbooks/roles/mailman3/templates/mailman-extra.cfg.j2
+++ b/playbooks/roles/mailman3/templates/mailman-extra.cfg.j2
@@ -5,7 +5,7 @@
 # a human.
 site_owner: "root@{{ ansible_fqdn }}"
 
-# We set this to less than the Exim's smtp_accept_max_per_host value.
+# We set this to less than the Exim's smtp_accept_queue_per_connection value.
 [mta]
 max_recipients: 45