Send Emails for your Node.js Application using Nodemailer + Express

Image by Muhammad Ribkhan from Pixabay

nodemailer is a simple module that has zero dependencies, designed specifically for sending emails. Follow along with this tutorial of a simple business scenario: a website sends a thank you email to new subscribers.

Step 1: Gmail setup

Nodemailer supports sending emails using Gmail. We do this by registering a Gmail account that uses two-factor authentication. Log in to your business’s Gmail account and open the Account > Security page.

Scroll down until you see ‘Signing in to Google’, then click on ‘2-Step Verification’ as shown below.

Follow the steps on the screen, and enable two-step verification.

When you return to the Account > Security page the 2-step verification should be displayed as shown below. You should see a new section called ‘App passwords’. Click it.

We need to set up a dedicated app password for our application for nodemailer to work.

Choose mail for the first parameter, and your <Insert OS> for the second parameter (my case: Mac), and select ‘Generate’ to generate a password.

Save the 16-digit password inside the yellow highlight for later use.

Step 2: Nodemailer Setup

Install nodemailer using npm install. Also, install express as well if you have not done so.

Set up a config object and fill out the keys as so.

• For host, use Simple Mail Transfer Protocol (SMTP) as the main transport for delivering messages.
• The port is the port to connect to, usually set at 587.
• The secure option is true if the connection will use TLS when connecting to the server. Set this to false.
• The auth is the authentication object, that will contain user, our sender email, and pass, the 16-digit password we set earlier.

Create a function that sends the email, with the parameter data that defines the email content.

The createTransport function creates a transporter object that sends the email. The transporter contains a module named sendMail that sends the email given data and a callback function that runs once the email is sent or had failed to send.

data contains the email content, and can be to be configured as such. The from should be your email and to your recipient’s email address. Fill in the subject title, and text thanking your subscribers for opting in.

You can also use html and attachment to send formatted text and attachments as files respectively.

Find out more about message configurations here.

Step 3: Set up Express

To test our nodemailer, we will set up a simple Express route. Set up a simple express application, start the server, and listen to local port 3000.

Now create an async POST request to send the email through the route /api/email. Our request body (req.body) should contain the data we set up above.

Step 4: Test nodemailer

We can test our setup through Postman, an API platform for building and using APIs. Click on the Body tab, select raw > JSON, and fill out the message configurations as such.

Click send, and the recipient will receive an email like so.