To send e-mails in a production environment, use services like Sendgrid.

Verify the e-mail address on the Sender Management page and create the SendGrid API key on the API keys page.

import nodemailer from 'nodemailer';
(async () => {
  const emailConfiguration = {
    auth: {
      user: process.env.EMAIL_USERNAME, // 'apikey'
      pass: process.env.EMAIL_PASSWORD
    },
    host: process.env.EMAIL_HOST, // 'smtp.sendgrid.net'
    port: process.env.EMAIL_PORT, // 465
    secure: process.env.EMAIL_SECURE, // true
  };
  const transport = nodemailer.createTransport(emailConfiguration);
  const info = await transport.sendMail({
    from: '"Sender" <sender@example.com>',
    to: 'recipient1@example.com, recipient2@example.com',
    subject: 'Subject',
    text: 'Text',
    html: '<b>Text</b>'
  });
  console.log('Message sent: %s', info.messageId);
})();

Demo

The demo with the mentioned example is available here.