- Add References header in read receipt (#1486681)

CHANGELOG

@@ -1,6 +1,7 @@
 CHANGELOG RoundCube Webmail
 ===========================
 
+- Add References header in read receipt (#1486681)
 - Fix database constraint violation when opening a message (#1486696)
 - Add 'loading' message while login is in progress (#1486667)
 - Fix quota_zero_as_unlimited (#1486662)

program/steps/mail/func.inc

@@ -1436,6 +1436,7 @@ function rcmail_send_mdn($uid, &$smtp_error)
       'Subject' => rcube_label('receiptread') . ': ' . $message->subject,
       'Message-ID' => sprintf('<%s@%s>', md5(uniqid('rcmail'.mt_rand(),true)), $RCMAIL->config->mail_domain($_SESSION['imap_host'])),
       'X-Sender' => $identity['email'],
+      'References' => trim($message->headers->references . ' ' . $message->headers->messageID),
     );
     
     if ($agent = $RCMAIL->config->get('useragent'))