protected function _validateEmail($email, $context)
    {
        if ($this->_emailPattern === null) {
            if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
                return;
            }
        } elseif (preg_match($this->_emailPattern, $email)) {
            return;
        }

        $context = ltrim($context, '_');
        if ($email == '') {
            throw new InvalidArgumentException(sprintf('The email set for "%s" is empty.', $context));
        }
        throw new InvalidArgumentException(sprintf('Invalid email set for "%s". You passed "%s".', $context, $email));
    }