Node.js mail sender helper file.

.env

COMPANY_NAME = your-company-name

MAIL_SERVICE = mail-service-name
MAIL_ADDRESS = yourname@yoursite.com
MAIL_PASSWORD = mail-password

mail.helper.js

'use strict';

const nodemailer = require('nodemailer')
  , pug = require('pug')
  , Promise = require('bluebird')
  , fs = Promise.promisifyAll(require('fs'));

const sendMail = (to, subject, mailContent, callback) => {
  // Create transporter
  const transporter = nodemailer.createTransport({
    service: process.env.MAIL_SERVICE,
    auth: {
      user: process.env.MAIL_ADDRESS,
      pass: process.env.MAIL_PASSWORD
    }
  });

  // Setup email data with unicode symbols
  let mailOptions = {
    from: process.env.COMPANY_NAME + ' <' + process.env.MAIL_ADDRESS + '>',
    to: to,
    subject: process.env.COMPANY_NAME + ' | ' + subject,
    html: mailContent
  };

  // Send mail
  transporter.sendMail(mailOptions, (error) => {
    if (error)
      callback(error, null);
    else
      callback(null, true);
  });
};

module.exports = (to, subject, content, callback) => {

  if (typeof content === 'object') {
    // Define template pug file and params
    const template = process.cwd() + '/app/views/mail_templates/' + content.view + '.pug'
      , params = content.params;

    // Read pug file
    fs
      .readFileAsync(template, 'utf8')
      .then((file) => {
        return pug.compile(file, {filename: template})(params);
      })
      .then((htmlContent) => {
        sendMail(to, subject, htmlContent, callback);
      }).catch((err) => {
        callback(err, null);
      });
  } else {
    sendMail(to, subject, content, callback);
  }
};