javamail code in servlet works locally, but not when uploaded to host

Trying to send an email with an xml attachment from a servlet (code
below) without success.

When I run my servlet locally all goes fine. The message is delivered.
When I upload to my host, messages are not delivered. I believe the
servlet runs fine because result data makes it back to my browser and
no exceptions are reported.

I've read that spam blockers will flag messages not really from the
server from which they claim to be. All is good here. The from is a
real account on my host's email server.

My host runs SpamAssassin. The message isn't delivered even when this
is disabled.

Any thoughts on this would be greatly appreciated.

Thanks

 // build a string from an XML document
      org.jdom.output.Format attachmentFmt =
org.jdom.output.Format.getCompactFormat();
      attachmentFmt.setOmitDeclaration(false);
      XMLOutputter attachmentOutputter = new
XMLOutputter(attachmentFmt);

      String attachXml =
attachmentOutputter.outputString(attachmentDoc);

      // We now have an xml string to attach. Let's get a javamail
message together
      // to which we can attach this xml. Got to do some server
properties stuff
      // first before we get to the message contents.
      String sServerName = "xxxx.xxxxxxx.com";
      String sUserName = "xxxxxx";
      String sPassword = "*******";

      Properties props = new Properties();
      props = System.getProperties();

      // fill props with any information
      props.put("mail.host", sServerName);
      props.put("mail.smtp.port", "25");
      props.put("mail.smtp.auth", "true");

      Session sess = Session.getDefaultInstance(props, null);
      MimeMessage message = new MimeMessage(sess);

      Transport transport = null;
      try {
        // String containing the contents of the message
        String sContent = "Test message."

        // Set the email message content to our name and address data
above
        message.setContent(sContent, "text/plain");

        // Hook up the message address and subject settings
        String sLNameFirst = sLastName +", " + sFirstName;
        String sFNameLast = sFirstName +" " + sLastName;

        Address fromAddress = new InternetAddress("xxxx@xxxx.com",
sLNameFirst);
        Address toAddress = new InternetAddress(sEmail, sLastName);

        message.setFrom(fromAddress);
        message.addRecipient(Message.RecipientType.TO, toAddress);
        message.setSubject("New auto quote attached for " +
sFNameLast);

        // Make a multipart message (part two being attachment) and
send
        // Create part one - the message
        BodyPart messageBodyPart = new MimeBodyPart();

        // Fill the message with our content string
        messageBodyPart.setText(sContent);

        // Add the message part to a multipart
        Multipart multipart = new MimeMultipart();
        multipart.addBodyPart(messageBodyPart);

        // Create part two - the attachment
        String sXMLAttachFileName = "autoquote_" + sLastName + "_" +
sFirstName;
        messageBodyPart = new MimeBodyPart();
        messageBodyPart.setText(attachXml);
        messageBodyPart.setFileName(sXMLAttachFileName);

        // Add attachment to the multipart
        multipart.addBodyPart(messageBodyPart);

        // Put parts in message
        message.setContent(multipart);

        // Send the message
        transport.connect(sServerName, sUserName, sPassword);
        transport.send(message);
        //Transport.send(message);

      }
      catch (MessagingException me){
        StringWriter sw = new StringWriter();
        me.printStackTrace (new PrintWriter(sw));
        pw.println(sw.toString());
      }