fundraiser after goal

add_action('wdf_after_goal_complete', 'fundraiser_done_send_email');
function fundraiser_done_send_email($pledges)
{
    $small_amount_emails = array();
    $large_amount_emails = array();
    foreach ($pledges as $pledge) {
        $data = get_post_meta($pledge->ID, 'wdf_transaction', true);
        if ($data['gross'] < 5) {
            $small_amount_emails[] = $data['payer_email'];
        } else {
            $large_amount_emails[] = $data['payer_email'];
        }
    }
    //this block for sending small donation amount
    $small_amount_emails = array_unique($small_amount_emails);
    $contents = "Chỉ dùng để thử nghiệm";
    $subject = "Email thử nghiệm";

    foreach ($small_amount_emails as $email) {
        wp_mail($email, $subject, $contents, array(
            "Content-type: text/html",
            "From: My Name <myname@example.com>"
        ));
    }
    //this block for sending larger donation amount
    $large_amount_emails = array_unique($large_amount_emails);
    $contents = "Chỉ dùng để thử nghiệm";
    $subject = "Email thử nghiệm";

    foreach ($large_amount_emails as $email) {
        wp_mail($email, $subject, $contents, array(
            "Content-type: text/html",
            "From: My Name <myname@example.com>"
        ));
    }
}