Sending email from own server to the internets

Question

I have set up an email server on my host. It's basically a SMTP server that listens on port 25.

const recvServer = new SMTPServer({
  requireTLS: true,
  authOptional: true,
  logger: true,      
  onConnect(session, callback) {
    return callback();
  },

  onMailFrom(address, session, callback) {
    console.log('from', address, session);
    return callback();
  },    

  onData(stream, session, callback) {
    console.log('new msg');
    let message = '';
    stream.on('data', chunk => {
      message += chunk;
    });

    stream.on('end', () => {

      callback(null, 'Message queued');
      simpleParser(message)
        .then(parsed => {
          console.log(parsed);
          // here I wish to forward the message to outside gmail addresses
        })
        .catch(err => {
          console.log(ee)
        });

    });
  }    
});

recvServer.listen(25);

recvServer.on('error', err => {
  console.log(err.message);
});

It works fine for receiving emails from outside, like gmail etc.

But I want to be able to send emails outside also, or forward emails that I receive to some gmail addresses.

I know that I can do that using Gmail SMTP servers, but then I need an gmail account and password.

I want to be able to send email with my own server, just like yahoo sends mail to gmail using their own server not gmail accounts :)

Answer 1

You need a MTA (Mail Transfer Agent) in order to send an email.

So the popular options is: Postfix, here a guid how to setup postfix on ubuntu: https://help.ubuntu.com/community/Postfix

Or you can spin up a docker container like: https://hub.docker.com/r/bytemark/smtp/

Then you can use nodemailer to send emails through postfix or docker instance.

And if you want there is a full stack docker image all batteries included: https://github.com/tomav/docker-mailserver

Answer 2

Technically you can use NodeMailer for sending emails.

"use strict";
const nodemailer = require("nodemailer");

// async..await is not allowed in global scope, must use a wrapper
async function main(){

  // Generate test SMTP service account from ethereal.email
  // Only needed if you don't have a real mail account for testing
  let testAccount = await nodemailer.createTestAccount();

  // create reusable transporter object using the default SMTP transport
  let transporter = nodemailer.createTransport({
    host: "smtp.ethereal.email",
    port: 587,
    secure: false, // true for 465, false for other ports
    auth: {
      user: testAccount.user, // generated ethereal user
      pass: testAccount.pass // generated ethereal password
    }
  });

  // send mail with defined transport object
  let info = await transporter.sendMail({
    from: '"Fred Foo 👻" <[email protected]>', // sender address
    to: "[email protected], [email protected]", // list of receivers
    subject: "Hello ✔", // Subject line
    text: "Hello world?", // plain text body
    html: "<b>Hello world?</b>" // html body
  });

  console.log("Message sent: %s", info.messageId);
  // Message sent: <[email protected]>

  // Preview only available when sending through an Ethereal account
  console.log("Preview URL: %s", nodemailer.getTestMessageUrl(info));
  // Preview URL: https://ethereal.email/message/WaQKMgKddxQDoou...
}

main().catch(console.error);