【PHP】マルチバイト対応メール送信

$to = "[email protected]";
$from = "[email protected]";
$subject = "件名";
$message = "本文";
$headers = [
  "From" => $from,
  "Sender" => $from,
  "Reply-To" => $from,
  "Organization" => "名前 <$from>",
  "X-Sender" => "名前",
  "X-Priority" => "3"
];
mb_language("Japanese");
mb_internal_encoding("UTF-8");
mb_send_mail($to, $subject, $message, $headers);