Verifique se o seu endereço IP está na lista negra - qual é o meu IP

The blacklist test will check a mail server IP address against the list of blacklisted ip stored on our database. If your mail server has been blacklisted, some email you send may not be delivered. Email blacklists are a common way of reducing spam. If you don't know your mail server's address, start with tchatche-france.fr and get all the information about your server.