nodemailer/nodemailer

const { SMTPServer } = require('smtp-server');
const nodemailer = require('nodemailer');

const SMTPServerInstance = new SMTPServer({
  logger: true,
  debug: true,
  authOptional: true
});

SMTPServerInstance.listen(() => {
  console.log('SMTP server is listening!\n');

  const transporter = nodemailer.createTransport({
    logger: true,
    debug: true,
    host: SMTPServerInstance.server.address().address,
    port: SMTPServerInstance.server.address().port,
    ignoreTLS: true
  });

  console.log('Sending email...');
  transporter
    .sendMail({
      from: 'sender@example.com',
      to: 'receiver@example.com',
      subject: 'Subject',
      text: 'Text',
      html: 'HTML'
    })
    .then((info) => {
      console.log('Email successfully sent!', info);
    })
    .catch((err) => {
      console.log('Error when sending an email:', err);
    })
    .finally(() => {
      SMTPServerInstance.close();
    });
});