diff --git a/core/email_api.php b/core/email_api.php
index d4ff2529c3..d132f0719d 100644
--- a/core/email_api.php
+++ b/core/email_api.php
@@ -959,6 +959,7 @@ function email_send( $p_email_data ) {
 	$mail->From = config_get( 'from_email' );
 	$mail->Sender = config_get( 'return_path_email' );
 	$mail->FromName = config_get( 'from_name' );
+	$mail->AddCustomHeader('Auto-Submitted:auto-generated');
 
 	if( OFF !== $t_debug_email ) {
 		$t_message = 'To: ' . $t_recipient . "\n\n" . $t_message;