Java Mailing Logic: Could not convert socket to TLS

In one application, I implemented mail sending logic using java. I used smtp.gmail.com over 587 port with a valid gmail id and password. In development environment everything is working fine. But in production environment I need to use a different mailing server say smtp.xyz.in over port 25 with a valid email id and password on that domain.

When I continue with SSL enable with following code:

I am getting an error

Could not convert socket to TLS

SunCertPathBuilderException: Unable To Find Valid Certification Path To Requested Target

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final ResourceBundle rsbd=ResourceBundle.getBundle("main/ResourceBundle/Dyna");

        // -- Attaching to default Session, or we could start a new one                                            

                    props.put("mail.smtp.host", smtpServer);

                props.put("mail.smtp.auth", "true");

                props.put("mail.debug", "true");

            props.put("mail.smtp.port", port); 

                props.put("mail.smtp.starttls.enable","true");

            props.put("mail.smtp.EnableSSL.enable","true");

  Session session =Session.getInstance(props, new Authenticator() {protected PasswordAuthentication getPasswordAuthentication() {return new PasswordAuthentication(admin_mail, admin_password);}});

         // -- Create a new message --
      Message msg = new MimeMessage(session);

     // -- Set the FROM and TO fields --
      msg.setFrom(new InternetAddress(from));

      msg.setRecipients(Message.RecipientType.TO, InternetAddress.parse(email, false));

      msg.setSubject(subject);
      msg.setText(emailContent);

      // -- Set some other header information --
      msg.setHeader("X-Mailer", "LOTONtechEmail");
      msg.setSentDate(new Date());

        // -- Send the message --
        Transport.send(msg);

When I am removing EnableSSL and trying by adding the following code:

(getting javax.mail.AuthenticationFailedException:535 5.7.3 Authentication unsuccessful)

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props.put("mail.smtp.socketFactory.port","25");

  props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");

  props.put("mail.smtp.socketFactory.fallback", "true");


  MailSSLSocketFactory sf=new MailSSLSocketFactory();

  sf.setTrustAllHosts(true);

  props.put("mail.smtp.ssl.socketFactory", sf);

By googling enough in last 3 days, I understand that I need to configure for trusted certificate like given here.

But I want to continue without encryption and without mugging to enable SSL. Is there a way to send emails by java programs through our own domain without enabling SSL. Any help will be appreciated.

Whether SSL/TLS is required or not is controlled by your mail server. If it requires it, you have to use it.

You can set the mail.smtp.ssl.trust property to ignore the certificate issue, or you can fix it as described in the JavaMail FAQ.