public function beforeAuthenticate(
        \Magento\Customer\Model\AccountManagement $subject,
        $username,
        $password
    ) {
        try {
            $mlmId = trim($username);
            $found = $this->daoDwnlCust->getByMlmId($mlmId);
            if ($found) {
                $custId = $found->getCustomerRef();
                $customer = $this->daoCust->getById($custId);
                if ($customer instanceof \Magento\Customer\Api\Data\CustomerInterface) {
                    $username = $customer->getEmail();
                }
            }
        } catch (\Throwable $e) {
            /* stealth exceptions */
        }
        return [$username, $password];
    }