How to verify an email address really exists by sending a mail in java
package csv;
    import javax.mail.PasswordAuthentication;
    import java.util.Properties;
    import javax.activation.DataHandler;
    import javax.activation.DataSource;
    import javax.activation.FileDataSource;
    import javax.mail.BodyPart;
    import javax.mail.Message;
    import javax.mail.MessagingException;
    import javax.mail.Multipart;
    import javax.mail.Session;
    import javax.mail.Transport;
    import javax.mail.internet.AddressException;
    import javax.mail.internet.InternetAddress;
    import javax.mail.internet.MimeBodyPart;
    import javax.mail.internet.MimeMessage;
    import javax.mail.internet.MimeMultipart;

    public class email {

public void send(String recipeintEmail,
        String subject,
        String messageText,String[] attachments)
        throws MessagingException, AddressException {
    /*
       It is a good practice to put this in a java.util.Properties
       file and encrypt password. Scroll down
       to comments below to see
       how to use java.util.Properties in JSF context.
    */
    String senderEmail = "our email address";
    String senderMailPassword = "password";
    String gmail = "smtp.gmail.com";

    Properties props = System.getProperties();

    props.put("mail.smtp.user", senderEmail);
    props.put("mail.smtp.host", "smtp.gmail.com");
    props.put("mail.smtp.port", "465");
    props.put("mail.smtp.starttls.enable", "true");
    props.put("mail.smtp.debug", "true");
    props.put("mail.smtp.auth", "true");
    props.put("mail.smtp.socketFactory.port", "465");
    props.put("mail.smtp.socketFactory.class",
          "javax.net.ssl.SSLSocketFactory");
    props.put("mail.smtp.socketFactory.fallback", "false");

    // Required to avoid security exception.
    email.MyAuthenticator authentication =
          new email.MyAuthenticator(senderEmail,senderMailPassword);
    Session session =
          Session.getDefaultInstance(props,authentication);
    session.setDebug(true);

    MimeMessage message = new MimeMessage(session);

    BodyPart messageBodyPart = new MimeBodyPart();
    messageBodyPart.setText(messageText);

    // Add message text
    Multipart multipart = new MimeMultipart();
    multipart.addBodyPart(messageBodyPart);

    // Attachments should reside in your server.
    // Example "c:file.txt" or "/home/user/photo.jpg"

    for (int i=0; i < attachments.length; i++) {

        messageBodyPart = new MimeBodyPart();
        DataSource source = new FileDataSource(attachments[i]);
        messageBodyPart.setDataHandler(new DataHandler(source));
        messageBodyPart.setFileName(attachments [i]);
        multipart.addBodyPart(messageBodyPart) ;
    }



    message.setContent(multipart);
    message.setSubject(subject);
    message.setFrom(new InternetAddress(senderEmail));
    message.addRecipient(Message.RecipientType.TO,
        new InternetAddress(recipeintEmail));

    Transport transport = session.getTransport("smtps");
    transport.connect(gmail,465, senderEmail, senderMailPassword);
    transport.sendMessage(message, message.getAllRecipients());

    transport.close();

}

private class MyAuthenticator extends javax.mail.Authenticator {
    String User;
    String Password;
    public MyAuthenticator (String user, String password) {
        User = user;
        Password = password;
    }

    @Override
    public PasswordAuthentication getPasswordAuthentication() {
        return new javax.mail.PasswordAuthentication(User, Password);
    }
}


public static void main(String args[]) throws MessagingException
{
    // email e=new email();
   // String at[]={"c:/COPYRIGHT.txt"};
  //  e.send("xyz@gmail.com", "hello","test"  )");
}

}