diff --git a/modules/exim/templates/exim4.conf.erb b/modules/exim/templates/exim4.conf.erb
index edf7b2e266..a29b1cfac0 100644
--- a/modules/exim/templates/exim4.conf.erb
+++ b/modules/exim/templates/exim4.conf.erb
@@ -55,7 +55,8 @@ CONFDIR = /etc/exim4
 # +local_domains, +relay_to_domains, and +relay_from_hosts, respectively. They
 # are all colon-separated lists:
 
-domainlist local_domains = @
+domainlist local_domains = @<% if mailman_domains.length > 0 -%>:<%= mailman_domains.join(":") %><% end -%>
+
 domainlist relay_to_domains =
 hostlist   relay_from_hosts = 127.0.0.1