diff --git a/roles/adm_instance/templates/config.env.inc.j2 b/roles/adm_instance/templates/config.env.inc.j2
index 944af8c578c5073db34e820fb5b8f307e1d72cfd..84d6c66a93326b18435889090a022b6f3294b1ae 100644
--- a/roles/adm_instance/templates/config.env.inc.j2
+++ b/roles/adm_instance/templates/config.env.inc.j2
@@ -9,4 +9,5 @@ function setSendingParams($mail) {
   $mail->Port     = {{ mail_port | default() }};
   $mail->Username = '{{ mail_username | default() }}';
   $mail->Password = '{{ mail_password | default() }}';
+  $mail->addCustomHeader('X-Mailer', 'ADM Mailer');
 }