diff --git a/core/lib/Drupal/Core/Mail/Plugin/Mail/PhpMail.php b/core/lib/Drupal/Core/Mail/Plugin/Mail/PhpMail.php
index 138257b8d..66bc193c2 100644
--- a/core/lib/Drupal/Core/Mail/Plugin/Mail/PhpMail.php
+++ b/core/lib/Drupal/Core/Mail/Plugin/Mail/PhpMail.php
@@ -99,10 +99,7 @@ public function mail(array $message) {
     // line-ending format appropriate for your system. If you need to
     // override this, adjust $settings['mail_line_endings'] in settings.php.
     $mail_body = preg_replace('@\r?\n@', $line_endings, $message['body']);
-    // For headers, PHP's API suggests that we use CRLF normally,
-    // but some MTAs incorrectly replace LF with CRLF. See #234403.
-    $mail_headers = str_replace("\r\n", "\n", $headers->toString());
-    $mail_subject = str_replace("\r\n", "\n", $mail_subject);
+    $mail_headers = $headers->toString();
 
     $request = \Drupal::request();