UnsupportedDataTypeException apenas fora do Eclipse

Olá pessoal,

Uso Javamail para envio de e-mail. Funciona perfeitamente quando usado no ambiente do Eclipse, mas se eu empacotar em um .jar ele gera um erro ao enviar, o que não faz muito sentido sendo que o código é exatamente o mesmo.

Alguém sabe o que pode estar acontecendo?

Valeu!

private static void send() throws MessagingException {
		
	System.out.println("Sending mail...");
        Properties props = new Properties();
        props.setProperty("mail.transport.protocol", "smtp");
        props.setProperty("mail.host", "server");

        Session mailSession = Session.getDefaultInstance(props, null);
        mailSession.setDebug(true);
        Transport transport = mailSession.getTransport();

        MimeMessage message = new MimeMessage(mailSession);
        message.setSubject("HTML  mail with images");
        message.setFrom(new InternetAddress("edson@dominio.com.br"));
        message.addRecipient(Message.RecipientType.TO, new InternetAddress("edson@dominio.com.br"));

        //
        // This HTML mail have to 2 part, the BODY and the embedded image
        //
        MimeMultipart multipart = new MimeMultipart("related");

        // first part  (the html)
        BodyPart messageBodyPart = new MimeBodyPart();
        String htmlText = "<H1>Hello</H1><img src=\"cid:image\">";
        messageBodyPart.setContent(htmlText, "text/html");

        // add it
        multipart.addBodyPart(messageBodyPart);
        
        // second part (the image)
        messageBodyPart = new MimeBodyPart();
        DataSource fds = new FileDataSource("C:\\temp\\logo.gif");
        messageBodyPart.setDataHandler(new DataHandler(fds));
        messageBodyPart.setHeader("Content-ID","<image>");

        // add it
        multipart.addBodyPart(messageBodyPart);

        // put everything together
        message.setContent(multipart);

        transport.connect();
        transport.sendMessage(message,message.getRecipients(Message.RecipientType.TO));
        transport.close();
	}
javax.activation.UnsupportedDataTypeException: no object DCH for MIME type multipart/related;boundary="----=_Part_0_10748354.1249932824934"
        at javax.activation.ObjectDataContentHandler.writeTo(Unknown Source)
        at javax.activation.DataHandler.writeTo(Unknown Source)
        at javax.mail.internet.MimeBodyPart.writeTo(MimeBodyPart.java:1350)
        at javax.mail.internet.MimeMessage.writeTo(MimeMessage.java:1683)
        at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:585)
        at TesteMail.teste3(TesteMail.java:99)
        at TesteMail.main(TesteMail.java:26)
Exception in thread "main" javax.mail.MessagingException: IOException while sending message;  nested exception is:
        javax.activation.UnsupportedDataTypeException: no object DCH for MIME type multipart/related;boundary="----=_Part_0_10748354.1249932824934"
        at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:625)
        at TesteMail.teste3(TesteMail.java:99)
        at TesteMail.main(TesteMail.java:26)
Caused by: javax.activation.UnsupportedDataTypeException: no object DCH for MIME type multipart/related;boundary="----=_Part_0_10748354.1249932824934"
        at javax.activation.ObjectDataContentHandler.writeTo(Unknown Source)
        at javax.activation.DataHandler.writeTo(Unknown Source)
        at javax.mail.internet.MimeBodyPart.writeTo(MimeBodyPart.java:1350)
        at javax.mail.internet.MimeMessage.writeTo(MimeMessage.java:1683)
        at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:585)
        ... 2 more