package javamail;

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;

public class JavaMailTest {
    public static void main(String[] args) {
        String host="host";
        final String user="username@domain.com";//change accordingly
        String to="username@domain.com";//change accordingly

        //Get the session object
        Properties props = new Properties();
        props.put("mail.smtp.host",host);
        props.put("mail.smtp.auth", "false");

        Session session=Session.getDefaultInstance(props, null);
        session.setDebug(true);

        //Compose the message
        try {
            MimeMessage message = new MimeMessage(session);
            message.saveChanges();
            message.setFrom(new InternetAddress(user));
            message.addRecipient(Message.RecipientType.TO,new InternetAddress(to));
            message.setSubject("Test mail");
            message.setText("This is test mail.");

            //send the message
            Transport.send(message);

            System.out.println("message sent successfully...");
        }
        catch (MessagingException e) {e.printStackTrace();}

    }
}

Transport.send(msg);
Folder sent = store.getFolder("Sent");
sent.appendMessages(new Message[] { msg });

com.sun.mail.util.MailConnectException:

 Couldn't connect to host, port: host, 25; timeout -1;
 nested exception is:   java.net.UnknownHostException: host

String host = "outlook.office365.com";
    Properties props = new Properties();
    props.put("mail.smtp.auth", "true");
    props.put("mail.smtp.starttls.enable", "true");
    props.put("mail.smtp.host", host);       //     mail server host
    props.put("mail.smtp.port", "587");      // port

Store store = session.getStore("imaps");
        store.connect("imap-mail.outlook.com", "username", "password");
        Folder folder = store.getFolder("Sent Items");
        folder.open(Folder.READ_WRITE);
        message.setFlag(Flag.SEEN, true);
        folder.appendMessages(new Message[] {message});
         store.close();