--- a/core/lib/Drupal/Component/Utility/Unicode.php	2017-05-13 13:59:50.262979285 +0300
+++ b/core/lib/Drupal/Component/Utility/Unicode.php	2017-05-13 14:00:57.890974455 +0300
@@ -606,7 +606,7 @@
    *   The mime-encoded header.
    */
   public static function mimeHeaderEncode($string) {
-    if (preg_match('/[^\x20-\x7E]/', $string)) {
+    if (preg_match('/[^\xA\xD\x20-\x7E]/', $string)) {
       $chunk_size = 47; // floor((75 - strlen("=?UTF-8?B??=")) * 0.75);
       $len = strlen($string);
       $output = '';