diff --git a/program/lib/Roundcube/rcube.php b/program/lib/Roundcube/rcube.php
index 4ac54072e..977f7784a 100644
--- a/program/lib/Roundcube/rcube.php
+++ b/program/lib/Roundcube/rcube.php
@@ -1578,10 +1578,12 @@ class rcube
      * @param string $body_file Location of file with saved message body (reference),
      *                          used when delay_file_io is enabled
      * @param array  $options   SMTP options (e.g. DSN request)
+     * @param bool   $disconnect Close SMTP connection ASAP
      *
      * @return boolean Send status.
      */
-    public function deliver_message(&$message, $from, $mailto, &$error, &$body_file = null, $options = null)
+    public function deliver_message(&$message, $from, $mailto, &$error,
+        &$body_file = null, $options = null, $disconnect = false)
     {
         $plugin = $this->plugins->exec_hook('message_before_send', array(
             'message' => $message,
@@ -1681,6 +1683,10 @@ class rcube
             fclose($msg_body);
         }
 
+        if ($disconnect) {
+            $this->smtp->disconnect();
+        }
+
         $message->headers($headers, true);
 
         return $sent;
diff --git a/program/steps/mail/func.inc b/program/steps/mail/func.inc
index 3f9503afa..19d7e7a8a 100644
--- a/program/steps/mail/func.inc
+++ b/program/steps/mail/func.inc
@@ -1910,7 +1910,7 @@ function rcmail_send_mdn($message, &$smtp_error)
         // SMTP options
         $options = array('mdn_use_from' => (bool) $RCMAIL->config->get('mdn_use_from'));
 
-        $sent = $RCMAIL->deliver_message($compose, $identity['email'], $mailto, $smtp_error, $body_file, $options);
+        $sent = $RCMAIL->deliver_message($compose, $identity['email'], $mailto, $smtp_error, $body_file, $options, true);
 
         if ($sent) {
             $RCMAIL->storage->set_flag($message->uid, 'MDNSENT');
diff --git a/program/steps/mail/sendmail.inc b/program/steps/mail/sendmail.inc
index e5e461c08..afaa7ac84 100644
--- a/program/steps/mail/sendmail.inc
+++ b/program/steps/mail/sendmail.inc
@@ -537,7 +537,7 @@ if (!$savedraft && !$saveonly) {
     $smtp_opts['dsn'] = $dsn_enabled;
 
     $sent = $RCMAIL->deliver_message($MAIL_MIME, $from, $mailto,
-        $smtp_error, $mailbody_file, $smtp_opts);
+        $smtp_error, $mailbody_file, $smtp_opts, true);
 
     // return to compose page if sending failed
     if (!$sent) {