mailman: Don't receive mails for UNIX system accounts

roles/mailman/templates/main.cf.j2

@@ -42,6 +42,7 @@ smtpd_milters = inet:localhost:11332
 non_smtpd_milters = $smtpd_milters
 
 alias_maps = hash:/var/lib/mailman/data/aliases
+local_recipient_maps = $alias_maps
 alias_database = $alias_maps
 
 milter_header_checks = pcre:/etc/postfix/milter_header_checks