postClient.print("Host: btslimayrac.ovh\n");// specifies the Internet host and port number of the resource being requested
postClient.print("Connection: close\n");// header option to signal that the connection will be closed after completion of the response
postClient.print("Content-Type: application/x-www-form-urlencoded\n");// values are encoded in key-value separated by '&', with a '=' between the key and the value
postClient.print("Content-Length: ");// indicates the size of the entity-body, in decimal number of bytes
postClient.print(postData.length());// to retrieve the size and send it