MailAPI.java (Subject doesn't work)

package model;

/**
 * External JARs:
 *
 * https://mvnrepository.com/artifact/javax.mail/javax.mail-api/1.6.2
 * https://mvnrepository.com/artifact/com.sun.activation/jakarta.activation/1.2.1
 * Ant Build.
 */

import java.util.HashMap;
import java.util.Properties;
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;
import javax.mail.Authenticator;
import javax.mail.Folder;
import javax.mail.Store;


public class MailAPI {

    private Properties props;
    private Session sess;
    private MimeMessage mimeMsg;

    private Store store;
    private Folder folder;
    private Message[] msgs;

    private String host;
    private String from;
    private char[] pwd;
    private String to;

    private String errorMsg;

    public MailAPI() {
        this.errorMsg = "";

        this.host = "pop.gmail.com";

        try {
            this.loadProperties();
            this.loadDefaultSender();
            this.loadSession();
            this.loadMimeMessage();
        } catch (Exception e) {
            errorMsg += "API initialization error: "+e.getMessage();
        }

    }

    public MailAPI(String prmEmail, char[] prmPassword){
        this.errorMsg = "";

        this.host = "pop.gmail.com";
        try {
            this.loadProperties();
            this.setSenderEmail(prmEmail);
            this.setSenderPassword(prmPassword);
            this.loadSession();
            this.loadMimeMessage();
        } catch (Exception e) {
            errorMsg += "API initialization error: "+e.getMessage();
        }
    }

    public String getError(){
        return errorMsg;
    }

    public String getTo(){
        return this.to;
    }

    public String getFrom(){
        return this.from;
    }

    public boolean emptyPassword(){
        return pwd.equals(null);
    }

    public void setSenderEmail(String prmEmail){
        from = prmEmail;
    }

    public void setSenderPassword(char[] prmPwd){
        pwd = prmPwd;
    }

    public void setRecipient(String prmEmail){
        to = prmEmail;
    }

    private void loadDefaultSender() throws Exception{
        this.from = "null@gmail.com"; // sender email (removed)
        this.pwd = new char[]{'n','u','l','l'}; // sender password (removed)
    }

    public void getEmails(){

        try {

            store = sess.getStore("pop3s");
            store.connect(host, from, String.valueOf(pwd));

            folder = store.getFolder("INBOX");
            folder.open(Folder.READ_WRITE);
            msgs = folder.getMessages();


            System.out.println("messages.length--- " + msgs.length);

            for (int i = 0, n = msgs.length; i < n; i++) {
                Message message = msgs[i];
                System.out.println("---------------------------------");
                System.out.println("Email Number " + (i + 1));
                System.out.println("Subject: " + message.getSubject());
                System.out.println("From: " + message.getFrom()[0]);
                System.out.println("Text: " + message.getContent().toString());

            }

            //close the store and folder objects
            folder.close(false);
            store.close();
            sess = null;
            msgs = null;


        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    public void sendMsg(String prmSub, String prmMsg){
        try {
            mimeMsg.addRecipient(Message.RecipientType.TO, new InternetAddress(to));
            mimeMsg.setSubject(prmSub); // not working
            mimeMsg.setText(prmMsg);

            Transport.send(mimeMsg);
        } catch (MessagingException e) {
            throw new RuntimeException(e);
        }
    }

    private void loadMimeMessage() throws Exception{
        mimeMsg = new MimeMessage(sess);
    }

    private void loadProperties() throws Exception{
        props = new Properties();
        //for SMTP
        props.put("mail.smtp.host", "smtp.gmail.com");
        props.put("mail.smtp.socketFactory.port", "465");
        props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.port", "465");

        //for POP3
        props.put("mail.store.protocol", "pop3");
        props.put("mail.pop3.host", "pop.gmail.com");
        props.put("mail.pop3.port", "995");
        props.put("mail.pop3.starttls.enable", "true");
    }

    private void loadSession() throws Exception{
        sess = Session.getDefaultInstance(props,new APIAuth());
    }

    private class APIAuth extends Authenticator{
        @Override
        protected PasswordAuthentication getPasswordAuthentication() {
            return new PasswordAuthentication(from, String.valueOf(pwd));
        }
    }
}