Send emails from wordpress using mailgun and wp hooks

functions.php

<?php
require_once VENDOR_PATH . 'autoload.php';
use Mailgun\Mailgun;

// WORDPRESS SHIT

// Email de aviso de post
function send_mail_post_pending_mailgun ($post_id, $post) {
  $mgClient = new Mailgun('KEY');
  $domain = "DOMAIN.COM";
  $post_status = get_post_status( $post );
  if( $post_status === 'pending' && ! wp_is_post_revision( $post ) ) {
    $email   = get_option( 'admin_email' );
    $subject = '[REVISAR NOVO POST] ' . get_the_title( $post );
    $message = 'Existe um novo post para revisão: ' . get_the_title( $post ) . "\n\n";
    $message .= 'Revisar o post: ' . admin_url( "post.php?post={$post_id}&action=edit" );
    
    $data = array('from' => 'Mailgun Sandbox <[email protected]>',
      'to'      => $email,
      'subject' => $subject,
      'text'    => $message);
    
    $mgClient->sendMessage($domain, $data);
  }
}

add_action('save_post', 'send_mail_post_pending_mailgun', 10, 2);
?>