public function normalizeOptions(array $options)
    {
        $options['useSsl'] = (bool) ($options['useSsl'] == 'SSL');
        $options['useStartTls'] = (bool) ($options['useStartTls'] == 'TLS');
        $options['accountCanonicalForm'] = $this->accountCanonicalFormMap[ $options['accountCanonicalForm'] ];

        return $options;
    }