A Beginner’s Guide to Sending Emails with Nodemailer in NodeJS

Welcome to a beginner's guide to Sending Emails using Nodemailer in NodeJS with Google API and Google OAuth 2.0!

This project serves as a comprehensive guide, offering testing and implementation insights for sending emails using Nodemailer in NodeJS with Google API and Google OAuth 2.0.

Table of Contents

• Introduction
• Getting Started
  • Installation
  • Environment Variable
• Quick Start
• Development Documentation
• To Do

Introduction

This project leverages Nodemailer with Google API and OAuth 2.0 to create a secure email-sending service. Using OAuth 2.0 for authentication ensures both efficiency and data protection for automated emails or newsletters.

This project's functionalities include:

• Sending emails using Google Apps.
• Sending emails using Ethereal Testing Server.
• Sending an embed image and a text file email with Google Apps.
• Sending (an embed image and a text file) email with Google API and Google OAuth 2.0.

Getting Started

I recommend running this project on NodeJS v20+ or NodeJS v22+. This project was originally run on NodeJS v21.7.1 and npm@10.5.0.

Installation

To get started, you need to download this project from the GitHub repository and navigate to the project's folder.

cd nodejs-nodemailer-gmail-api/

You need to dowload the project's dependencies.

npm install

Additionally, you should download an extra package for running the project, it's called nodemon.

npm i nodemon --save-dev

Environment Variable

This step is important! Create an .env file to store the application's credentials. These are the credentials you will need.

BE_PORT="" # IMPORTANT: This is the back end port, you need to have this variable for the project to work!
GMAILHOST=smtp.gmail.com
GMAILUSER=""
APPPASSWORD=""
ETHEREALHOST=smtp.ethereal.email
GOOGLE_CLIENT_ID=""
GOOGLE_CLIENT_SECRET=""
GOOGLE_PLAYGROUND_REDIRECT_URI=""
GOOGLE_PLAYGROUND_REFRESH_TOKEN=""

Quick Start

Run the project using the following command(s).

npm start

Or, if you have already downloaded nodemon using npm i nodemon --save-dev, you can also run the project using the following commands(s).

npm run api

These are the URLs that will be accessed. P.S: I will add the Postman docs as soon as possible.

.../api/v1/emails/send-email
.../api/v1/emails/send-email-ethereal
.../api/v1/emails/send-email-embed-attach
.../api/v1/emails/send-email-google-api

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Development Documentation

Order from newest to oldest

13/10/2024

• Note: this note involve using Google API and Google OAuth 2.0 involving invalid_grant, this error is because the access/refresh token is incorrect or invalid, this often happens because some Google API's refresh token in "Testing" mode only last for 7 days. To fix this, you just need to supply the project with a newly created Refresh Token.

14/07/2024

• Note: Email Server Client which supports HTML format will render the HTML format, Email Server Client which supports text will render text. More information here: https://chatgpt.com/share/877de70d-73b7-44d3-b791-cb26601db92c

03/06/2024

• Feature: send emails using google api

21/05/2024

• Feature: send emails using ethereal server

14/05/2024

• Utils: add request logger and request limiter

04/05/2024

• Initialize: the project