Answer by Shreshth Kharbanda for Sending Email in Android using JavaMail API without using the default/built-in app

I found a shorter alternative for others who need help. The code is:

package com.example.mail;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 SendMailTLS {    public static void main(String[] args) {        final String username = "username@gmail.com";        final String password = "password";        Properties props = new Properties();        props.put("mail.smtp.auth", "true");        props.put("mail.smtp.starttls.enable", "true");        props.put("mail.smtp.host", "smtp.gmail.com");        props.put("mail.smtp.port", "587");        Session session = Session.getInstance(props,          new javax.mail.Authenticator() {            protected PasswordAuthentication getPasswordAuthentication() {                return new PasswordAuthentication(username, password);            }          });        try {            Message message = new MimeMessage(session);            message.setFrom(new InternetAddress("from-email@gmail.com"));            message.setRecipients(Message.RecipientType.TO,                InternetAddress.parse("to-email@gmail.com"));            message.setSubject("Testing Subject");            message.setText("Dear Mail Crawler,"+"\n\n No spam to my email, please!");            Transport.send(message);            System.out.println("Done");        } catch (MessagingException e) {            throw new RuntimeException(e);        }    }}

Source: Sending Email via JavaMail API

Hope this Helps! Good Luck!