Adding addiotional email from products custom field

Question

I am trying to add a new email to order confirmation. Now I am able to use the order's custom fields to ad a new extra email address. But i would like to use a custom field from the product instead.

Below is what I have done so far.

add_filter( 'woocommerce_email_recipient_new_order', 'additional_customer_email_recipient', 10, 2 ); // New Order 
function additional_customer_email_recipient( $recipient, $order ) {
    if ( ! is_a( $order, 'WC_Order' ) ) return $recipient;

    $prod_id = get_the_ID();
    $extra_mail = get_post_meta($prod_id,'extra_email',true);
    $recipient = $extra_mail;

    return $recipient;
}