public function isMappedUserExistInUsersTable() {

        // get the mapped recipient (valid because $this->isInboundEmailToEmailAddressMapToUser() is already done)
        $mappedRoutes = config('lasallecmsmailgun.inbound_map_mailgun_routes_with_user_email_address');

        foreach ($mappedRoutes as $route => $user) {

            // if "from" email address is the same as the route specified in the config...
            if ($this->request->input('recipient') == $route) {
                $userEmailAddress = $user;
            }
        }

        if ($this->userRepository->findUserIdByEmail($userEmailAddress)) {
            return true;
        }

        return false;
    }