You can use Gmail SMTP via TLS

You can use Gmail SMTP via TLS

final String username = "username@gmail.com";
final String password = "password";

Properties prop = new Properties();
prop.put("mail.smtp.host", "smtp.gmail.com");
prop.put("mail.smtp.port", "587");
prop.put("mail.smtp.auth", "true");
prop.put("mail.smtp.starttls.enable", "true"); //TLS

Session session = Session.getInstance(prop,
 new javax.mail.Authenticator() {
  protected PasswordAuthentication getPasswordAuthentication() {
   return new PasswordAuthentication(username, password);
  }
 });

try {

 Message message = new MimeMessage(session);
 message.setFrom(new InternetAddress("from@gmail.com"));
 message.setRecipients(
  Message.RecipientType.TO,
  InternetAddress.parse("[email protected], [email protected]")
 );
 message.setSubject("Testing Gmail TLS");
 message.setText("Dear Mail Crawler," +
  "\n\n Please do not spam my email!");
 
 Transport.send(message);

 System.out.println("Done");
 
} catch (MessagingException e) {
 e.printStackTrace();
}

I recommend you to visit your Google Account and generate a new Application Password , this allows your password field to be encoded and not used as plain text

private static String USER_NAME = "Gmail Username";  // GMail user name (just the part before "@gmail.com")
private static String PASSWORD = "gbxxfgfhujdfqndd"; // GMail password

public static boolean sendEmail(String RECIPIENT, String sub, String title, String body, String under_line_text,
 String end_text) {
 String from = USER_NAME;
 String pass = PASSWORD;
 String[] to = {
  RECIPIENT
 }; // list of recipient email addresses
 String subject = sub;
 Properties props = System.getProperties();
 String host = "smtp.gmail.com";
 props.put("mail.smtp.starttls.enable", "true");
 props.put("mail.smtp.host", host);
 props.put("mail.smtp.user", from);
 props.put("mail.smtp.password", pass);
 props.put("mail.smtp.port", "587");
 props.put("mail.smtp.auth", "true");

 Session session = Session.getDefaultInstance(props);
 MimeMessage message = new MimeMessage(session);

 try {
  message.setFrom(new InternetAddress(from));
  InternetAddress[] toAddress = new InternetAddress[to.length];

  // To get the array of addresses
  for (int i = 0; i < to.length; i++) {
   toAddress[i] = new InternetAddress(to[i]);
  } 

  for (int i = 0; i < toAddress.length; i++) {
   message.addRecipient(Message.RecipientType.TO, toAddress[i]);
  }

  message.setSubject(subject);
  BodyPart messageBodyPart = new MimeBodyPart();
  String htmlText = "<div style=\" background-color: white;width: 25vw;height:auto;border: 20px solid grey;padding: 50px;margin:100 auto;\">\n" +
   "<h1 style=\"text-align: center;font-size:1.5vw\">" + title + "</h1>\n" + "<div align=\"center\">" +
   "<h2 style=\"text-align: center;font-size:1.0vw\">" + body + "</h2>" +

   "<h3 style=\"text-align: center;text-decoration: underline;text-decoration-color: red;font-size:0.9vw\">" +
   under_line_text + "</h3><br><h4 style=\"text-align: center;font-size:0.7vw\">" + end_text +
   " </h4></div>";
  messageBodyPart.setContent(htmlText, "text/html");

  Multipart multipart = new MimeMultipart(); 

  // Set text message part
  multipart.addBodyPart(messageBodyPart);
  message.setContent(multipart);

  Transport transport = session.getTransport("smtp");
  transport.connect(host, from, pass);
  transport.sendMessage(message, message.getAllRecipients());
  transport.close();
 } catch (AddressException ae) {
  ae.printStackTrace();
 } catch (MessagingException me) {
  me.printStackTrace();
 }
 return true;
}

Output:

Also you can change BodyPart accordingly i have included an html responsive template

I recommend you to visit your Google Account and generate a new Application Password , this allows your password field to be encoded and not used as plain text

Otherwise you will come up with this exception

javax.mail.AuthenticationFailedException: 534-5.7.9 Application-specific password required.

Hope it helped!