JAVA code for mail server - "server is null"

Question

I've been working on this JAVA code that is supposed to send an email. Here's the code:

package sendemail;
import java.io.UnsupportedEncodingException;  
import java.util.Properties;  
import java.util.logging.Level;  
import java.util.logging.Logger;  
import javax.mail.Authenticator;  
import javax.mail.Message;  
import javax.mail.MessagingException;  
import javax.mail.PasswordAuthentication;  
import javax.mail.Session;  
import javax.mail.Transport;  
import javax.mail.internet.InternetAddress;  
import javax.mail.internet.MimeMessage;  

public class MAIN {  

private String SMTP_HOST = "smtp.gmail.com";  
private String FROM_ADDRESS = "sender@gmail.com";  
private String PASSWORD = "pass";  
private String FROM_NAME = "user";  

public boolean sendMail(String[] recipients, String[] bccRecipients, String subject, String message) {  
    try {  
        Properties props = (Properties)System.getProperties().clone();

        //Bypass the SSL authentication
        props.put("mail.smtp.starttls.enable", true);
        props.put("mail.smtp.starttls.required", true);
        props.put("mail.smtp.ssl.enable", "true"); 
        props.put("mail.smtp.host", SMTP_HOST);  
        props.put("mail.smtp.auth", true);  
        props.put("mail.debug", "false");   
        props.put("mail.smtp.port", "587");



        Session session = Session.getInstance(props, new SocialAuth());  
        Message msg = new MimeMessage(session);  

        InternetAddress from = new InternetAddress(FROM_ADDRESS, FROM_NAME);  
        msg.setFrom(from);  

        InternetAddress[] toAddresses = new InternetAddress[recipients.length];  
        for (int i = 0; i < recipients.length; i++) {  
            toAddresses[i] = new InternetAddress(recipients[i]);  
        }  
        msg.setRecipients(Message.RecipientType.TO, toAddresses);  


        InternetAddress[] bccAddresses = new InternetAddress[bccRecipients.length];  
        for (int j = 0; j < bccRecipients.length; j++) {  
            bccAddresses[j] = new InternetAddress(bccRecipients[j]);  
        }  
        msg.setRecipients(Message.RecipientType.BCC, bccAddresses);  

        msg.setSubject(subject);  
        msg.setContent(message, "text/plain");  
        Transport.send(msg);  
        return true;  
    } catch (UnsupportedEncodingException ex) {  
        Logger.getLogger(MAIN.class.getName()).log(Level.SEVERE, null, ex);  
        return false;  

    } catch (MessagingException ex) {  
        Logger.getLogger(MAIN.class.getName()).log(Level.SEVERE, null, ex);  
        return false;  
    }  
}  

class SocialAuth extends Authenticator {  

    @Override  
    protected PasswordAuthentication getPasswordAuthentication() {  

        return new PasswordAuthentication(FROM_ADDRESS, PASSWORD);  

    }  
}  
}
 package sendemail;

import sendemail.MAIN;

public class BIGMAIN {  

public static void main(String[] args) {  
    String[] recipients = new String[]{"rec@gmail.com"};  
    String[] bccRecipients = new String[]{"rec@gmail.com"};  
    String subject = "Hi this is test Mail";  
    String messageBody = "Test Mail from codesstore.blogspot.com";  

    new MAIN().sendMail(recipients, bccRecipients, subject, messageBody);  

}  
}  

But whenever I run it I get this error:

 javax.mail.SendFailedException: Sending failed;
 nested exception is: 
 javax.mail.MessagingException: 530 5.7.0 Must issue a STARTTLS command    first. h7sm10262673wmf.9 - gsmtp

at javax.mail.Transport.send0(Transport.java:219)
at javax.mail.Transport.send(Transport.java:81)
at sendemail.send.main(send.java:39)

I've searched for this error and found out that adding the following line to the code should solve the problem, but the problem is still here and sometimes I get a message that says the server is null:

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