Out-of-the-Box - Add User Roles to Email Notification

/* Add User Roles to Email Notification */
add_filter('outofthebox_notification', 'user_role_notification', 10, 1);

function user_role_notification($notification) {

    $additional_recipients = array();
    foreach ($notification['recipients'] as $key => $recipient) {

        /* Skip placeholders and emailaddresses */
        if (strpos($recipient, '%') !== false || strpos($recipient, '@') !== false) {
            continue;
        }

        /* Check if recipient is an User Role */
        if (is_a(get_role($recipient), 'WP_Role')) {
            $users = get_users('role=' . $recipient);

            /* Add all emailaddresses for User Role */
            foreach ($users as $user) {
                $additional_recipients[] = $user->user_email;
            }

            unset($notification['recipients'][$key]);
        }
    }

    /* Make sure that there aren't any duplicates in the list of recipients */
    $notification['recipients'] = array_merge($notification['recipients'], $additional_recipients);
    $notification['recipients'] = array_unique(array_map('trim', $notification['recipients']));

    return $notification;
}