<?php

//Example:
// USE a custom value: filter-id:fv-meta-email

add_action('fv/approve_photo', function($competitor_id, $admin_comment, $competitor) {
  add_filter('notification/recipient/email/fv-meta-email', function($value) {
    return $competitor->meta()->get_value( "meta_key" );
  });
}, 10, 3);