TransportExceptionInterface

class \Symfony\Component\Mailer\Exception\HttpTransportException extends \Symfony\Component\Mailer\Exception\TransportException
class \Symfony\Component\Mailer\Exception\TransportException extends \Symfony\Component\Mailer\Exception\RuntimeException implements \Symfony\Component\Mailer\Exception\TransportExceptionInterface
class \Symfony\Component\Mailer\Exception\UnexpectedResponseException extends \Symfony\Component\Mailer\Exception\TransportException