Send emails in Node.js using Nodemailer, Gmail & oAuth2

In this article, I'm gonna discuss How to configure your gmail account for sending emails in node.js using nodemailer & oAuth2.

Previously, we had an option for sending emails in node.js via gmail by allowing less secure apps in your gmail settings, but now google has removed that feature for security reasons and so we have to go through several steps to send emails from your official Gmail account.

Let's get started!

Set up your project

Go to Google Developer console and create a new project

Configure oAuth consent screen

• Select your project

• Go to API & Services tab

Select oAuth consent screen from the dropdown

1. Select external and then hit create

2. Enter all the details carefully, then click save and continue

3. In scops, click save and continue

4. In Test users, enter your email address which you would like to use for sending emails

Create credentials for your project

• Click on credentials in the side menu

• Click on create credentials

  1. Select oAuth client ID from the dropdown

  2. Select your application type

  3. Scroll down to Authorised redirect URIs & add this URI developers.google.com/oauthplayground

  4. Copy and save your client ID & client secret

Get the refresh and access token

• Now go to developers.google.com/oauthplayground

• On the top-right corner, click the settings icon

  1. Mark Use your own OAuth credentials

  2. Enter the Client ID & Secret we've copied before

• Now, in the left side, scroll down and select Gmail API v1

• Select mail.google.com

• Click on Authoirse APIs

• Select your account (which you've added as Test user in the Google developer console)

• Now, click on Exchange authorise code for tokens

Copy and save refresh & access token

Set up Nodemailer & Send your first email

First of all you will have to create a .env and this file should include the following

• USER_EMAIL: the email you have used in your google configuration

• CLIENT_ID: it's the same client-id that we've got on the google developer console

• CLIENT_SECRET: it's the same client-secret that we've got on google developer console

• REFRESH_TOKEN: this is the refresh token we've generated on oAuth2 playground

• ACCESS_TOKEN: this is the access token we've generated on oAuth2 playground

1. Let's install all important modules

     npm install nodemailer googleapis dotenv
   

   nodemailer is the module for sending email node.js, googleapis would be used for setting google account, and the dotenv module is just to make use of your environment variables

2. Now, add the modules to your main file

     require("dotenv").config()
     const nodemailer = require("nodemailer");
     const { google } = require("googleapis");
     const OAuth2 = google.auth.OAuth2;
   

3. Let's create the Transport function

     const createTransporter = async () => {
       try {
         const oauth2Client = new OAuth2(
             process.env.CLIENT_ID,
             process.env.CLIENT_SECRET,
             "https://developers.google.com/oauthplayground"
           );
   
           oauth2Client.setCredentials({
             refresh_token: process.env.REFRESH_TOKEN,
           });
   
           const accessToken = await new Promise((resolve, reject) => {
             oauth2Client.getAccessToken((err, token) => {
               if (err) {
                 console.log("*ERR: ", err)
                 reject();
               }
               resolve(token); 
             });
           });
   
           const transporter = nodemailer.createTransport({
             service: "gmail",
             auth: {
               type: "OAuth2",
               user: process.env.USER_EMAIL,
               accessToken,
               clientId: process.env.CLIENT_ID,
               clientSecret: process.env.CLIENT_SECRET,
               refreshToken: process.env.REFRESH_TOKEN,
             },
           });
           return transporter;
       } catch (err) {
         return err
       }
     };
   

   This function is to get ready your google account for sending emails

4. Now let's create our main function to send emails

     const sendMail = async () => {
       try {
         const mailOptions = {
           from: process.env.USER_EMAIL,
           to: req.body.email,
           subject: "Test",
           text: "Hi, this is a test email",
         }
   
         let emailTransporter = await createTransporter();
         await emailTransporter.sendMail(mailOptions);
       } catch (err) {
         console.log("ERROR: ", err)
       }
     };
   

5. Now let's call our function

     sendEmail()
   

   Bingo! time to check your email!