Java - Problemas al enviar un correo.

hola, tengo este codigo

Properties properties =System.getProperties();
properties.put("mail.smtp.host", servidorSmtp);
properties.put("mail.transport.protocol", "smtp");
properties.put("mail.from",from);
Session session = Session.getDefaultInstance(properties, null);

MimeMessage message = new MimeMessage(session);
InternetAddress[] address = {new InternetAddress(to)};
message.setRecipients(Message.RecipientType.TO, address);
message.setFrom(new InternetAddress(from));
message.setSubject(subject);
message.setContent(mensaje,"text/plain");

Transport transport = session.getTransport(address[0]);
transport.connect();
transport.sendMessage(message,address); <======= ME FALLA AQUI
transport.close();

me falla en esta sentencia.....

transport.sendMessage(message,address);

no me envia el correo no sé por qué.

las trazas me dicen esto,

DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun Microsystems, Inc]
DEBUG SMTP: useEhlo true, useAuth false

DEBUG: SMTPTransport trying to connect to host "mismtp", port 25

DEBUG SMTP RCVD: 220 mismtp Microsoft ESMTP MAIL Service, Version: 5.0.2195.2096 ready at Fri, 24 Aug 2001 08:50:42 +0200

DEBUG: SMTPTransport connected to host "mismtp", port: 25

DEBUG SMTP SENT: EHLO pc020
.....
DEBUG SMTP SENT: MAIL FROM:[email protected]>
DEBUG SMTP RCVD: 250 2.1.0 a@