public static function checkForEmail($template, $email)
    {
        if (in_array($template, static::$safeTemplates)) {
            return [];
        }

        if (empty($email)) {
            return [];
        }

        if (!is_array($email)) {
            $email = [$email => null];
        }

        $emails = array_keys($email);

        return static::where(function($q) use ($template) {
                $q->where('template', $template)->orWhere('template', '*');
            })
            ->whereIn('email', $emails)
            ->lists('email');
    }