Send email to administrator when user registers form custom registration form

functions.php

add_action('wplms_custom_registration_form_user_added',function($user_id,$user_args,$settings){
  $admins = get_users('role=Administrator');
  $admin_emails = []; //PHP 7.2+ else change to $admin_Emails = array();
  foreach ($blogusers as $user) {
        $admin_emails[]=$user->user_email;
  }
  $admin_emails = implode(',',$admin_emails);

$subject = 'User registered in site';
$body = 'The user '.$user_args['user_email'].' registered in your site';
$headers = array('Content-Type: text/html; charset=UTF-8','From: YourSite <FROM EMAIL.com>');
    wp_mail( $admin_emails, $subject, $message, $headers, $attachments );
});