mw wp form で管理者宛メールを送信しない

index.php

<?php
//略
add_filter('mwform_admin_mail_mw-wp-form-xxx', [$this, 'adminMailBlock'], 9, 3);
//略
public function adminMailBlock($Mail, $values, $Data){
  $Mail->to = '';
  add_filter( 'mwform_is_mail_sended', function(){
    return true;
  } );
  return $Mail;
}