How to Send an Email with Nodemailer

Nodemailer creators say that it makes sending an email a piece of cake. Let’s see if they are talking about cooking or eating 🙂 The idea of this article is to explain how to use Nodemailer for email sending. We will focus mainly on SMTP and HTML aspects but will also do an overview of all Nodemailer capabilities. Besides, this tutorial will help you prepare and test email messages to send out with your Node.js application.

If you want to read the full article, check it out on the Mailtrap’s blog - How to Send an Email with Nodemailer

How to use Nodemailer

Installation

The only thing required to start using Nodemailer is Node.js version 6.0 or above. You should also install Nodemailer itself but it’s really easy with the npm or Yarn package manager. Execute the following command in the Node.js command prompt:

npm install nodemailer
or
yarn add nodemailer

Once completed, include it into your application like this:

var nodemailer = require('nodemailer');

or this if you are using ES modules:

import nodemailer from ‘nodemailer’;

Sending messages

To send a message with Nodemailer, there are three main steps.

Step 1. Create Nodemailer transporter

SMTP is the most common transporter, and below we will describe it in more detail, as well as demonstrate some examples. But there is a list of other available options:

• Built-in transports
• sendmail, a regular sendmail command for simple messages. It’s similar to the mail() function in PHP
• SES , to handle large traffic of emails by sending them using Amazon SES
• stream, a buffer for testing purposes, to return messages.

-_ External transport. To put it simply, you can create your own transportation method._

For more details, refer to the Nodemailer documentation.

With SMTP, everything is pretty straightforward. Set host, port, authentication details and method, and that’s it. It’s also useful to verify that SMTP connection is correct at this stage: *add verify(callback) * call to test connection and authentication.

transporter.verify(function(error, success) {
   if (error) {
        console.log(error);
   } else {
        console.log('Server is ready to take our messages');
   }
});

How to test emails in Nodemailer?

To test emails sent with Nodemailer, we will use Mailtrap, an online tool for complex email testing in a pre-production environment. It will catch our messages, display how they look in a real email client, and help analyze and debug them. Mailtrap also provides Bcc testing options and allows you to share your email testing results with other team members, as well as forward emails to the real verified addresses.

Even If you don’t have an account yet, the whole set up process takes just a couple of minutes. Mailtrap integrates as a regular SMTP server. Quickly sign up (it’s free), go to the SMTP settings tab in your Inbox, copy the necessary settings, and insert them to your application script.

Mailtrap offers a ready-to-use integration with Nodemailer: select it from the Integrations section and insert it into your application code. It already contains transporter and syntaxis attributes:

var transport = nodemailer.createTransport({
  host: "smtp.mailtrap.io",
  port: 2525,
  auth: {
    user: "1a2b3c4d5e6f7g", //generated by Mailtrap
    pass: "1a2b3c4d5e6f7g" //generated by Mailtrap
  }
});

Otherwise, you can use auto-generated email test accounts on Ethereal, which is also a fake SMTP service, mostly aimed at Nodemailer users.

Recently, Nodemailer has introduced NodemailerApp. It provides Sendmail replacement, but first of all, is designed to debug emails. NodemailerApp has SMTP and POP3 local servers, a catchall email domain service, along with email preview capabilities.

Step 2. Set Nodemailer message options

At this point, we should specify the sender, message recipients, and the content of our message.

Remember, Unicode is supported, so you can include emojis as well!

To send a text formatted as HTML, no extra attributes are required, just put your HTML body into the message with an html attribute. For advanced templates, you can add attachments and embed images. Let’s take a look at this example of simple message options first:

var mailOptions = {
    from: '"Example Team" <from@example.com>',
    to: 'user1@example.com, user2@example.com',
    subject: 'Nice Nodemailer test',
    text: 'Hey there, it’s our first message sent with Nodemailer ;) ',
    html: '<b>Hey there! </b><br> This is our first message sent with Nodemailer'
};

Attachments in Nodemailer

You can add different types of data to your message in Nodemailer using the following main properties:

• filename: the name of the attached file. Here you can use Unicode as well.
• content: the body of your attachment. It can be a string, a buffer, or a stream.
• path: path to the file, to stream it instead of including it in the message. It is a good option for big attachments.
• href: attachment URL. Data URIs are also supported.

 list: {
            // List-Help: <mailto:admin@example.com?subject=help>
            help: 'admin@example.com?subject=help',

            // List-Unsubscribe: <http://example.com> (Comment)
            unsubscribe: [
                {
                    url: 'http://example.com/unsubscribe',
                    comment: 'A short note about this url'
                },
                'unsubscribe@example.com'
            ],

            // List-ID: "comment" <example.com>
            id: {
                url: 'mylist.example.com',
                comment: 'my new list'
            }
        }
    };

Optional properties let you add specific content types or inline images.

contentType: if you don’t set it, it will be inferred from the filename property

` // An array of attachments
    attachments: [
        // String attachment
        {
            filename: 'notes.txt',
            content: 'new important notes',
            contentType: 'text/plain' // optional, would be detected from the filename
        },

`
CID: inline images in the HTML message. For more details on attaching images to HTML emails, read this post. Note that the CID value should be unique.

cid: 'note@example.com' // should be as unique as possible
            },

            // File Stream attachment
            {
                filename: 'matrix neo.gif',
                path: __dirname + '/assets/neo.gif',
                cid: 'neo@example.com' // should be as unique as possible
            }
        ],

Encoding: can be added to the string type of content. It will encode the content to a buffer type according to the encoding value you set (base64, binary, etc.)

     `   // Binary Buffer attachment
        {
            filename: 'image.png',
            content: Buffer.from(
                'iVBORw0KGgoAAAANSUhEUgAAABAAAAAQAQMAAAAlPW0iAAAABlBMVEUAAAD/' +
                    '//+l2Z/dAAAAM0lEQVR4nGP4/5/h/1+G/58ZDrAz3D/McH8yw83NDDeNGe4U' +
                    'g9C9zwz3gVLMDA/A6P9/AFGGFyjOXZtQAAAAAElFTkSuQmCC',
                'base64'
            )`

Step 3. Deliver a message with sendMail()

Once we created a transporter and configured a message, we can send it using the sendMail() method:

transport.sendMail(mailOptions, (error, info) => {
        if (error) {
            return console.log(error);
        }
        console.log('Message sent: %s', info.messageId);
});

Nodemailer capabilities

We have covered the info on how to create and send an email in Nodemailer via SMTP, experimenting with different types of content: HTML, tables, lists, attachments, and embedded images.What is good about Nodemailer is that it offers a bunch of various options and settings, so you can customize every piece of your email.

To get Nodemailer examples and learn more about debugging options in Nodemailer - read our full How to Send an Email with Nodemailer article.