Email sending feature is a-must in almost every application. Here is the tutorial on how we can send email using nodemailer and OAuth 2.0 🚀🔥&nbsp; This first step is crucial as we need client ID and client secret which will be later added in the OAuth2 playground to enable mail. First, we need to sign-in to <a href="https://console.cloud.google.com/welcome" target="_blank" rel="noopener">google cloud console</a>. If you have not created a project there, you need to create one and also set up a consent screen.&nbsp; For now, I&rsquo;m assuming we already have that. On the side menu, go to the &ldquo;APIs and services&rdquo; menu and click on &ldquo;Credentials&rdquo;. After that click on &ldquo;CREATE CREDENTIALS&rdquo; in the top-middle section. A dropdown menu will appear. From there, click on OAuth client ID. After that, select the application type you need (for now: Web application) and fill up the name you want. For &ldquo;Authorised redirect URIs&rdquo;, add this URI:&nbsp;<a href="https://developers.google.com/oauthplayground">https://developers.google.com/oauthplayground</a>. This URI is of OAuth 2.0 playground. Now click on &ldquo;CREATE&rdquo;. 
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<img style="display: block; margin-left: auto; margin-right: auto;" src="../../api/file-read/uploads/e50fc64c7971cd4dd64ac1f01" width="832" height="258">
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 Note: the created project might take a few minutes to hours to come into effect.
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Right after creating, we will get client ID and client secret. Now go to <a href="https://developers.google.com/oauthplayground" target="_blank" rel="noopener">OAuth 2.0 playground</a>.&nbsp; &nbsp;
 <img style="display: block; margin-left: auto; margin-right: auto;" src="../../api/file-read/uploads/e50fc64c7971cd4dd64ac1f02" width="796" height="355"> 
On the right top, click on the setting icon. There we will see different options but one we need appears after checking on &ldquo;Use your own OAuth credentials&rdquo;. After checking, input fields with client ID and client secret appear. Paste those credentials we got from google console and close it. After that on the right panel in &ldquo;Step 1&rdquo;, search for &ldquo;Gmail API v1&rdquo; and click on &ldquo;<a href="https://mail.google.com/">https://mail.google.com/</a>&rdquo;. Click on the &ldquo;Authorize APIs&rdquo; button. After success, Step 2 will be active and we can see the Authorization code and exchange button just below it. Click on the button. Now we will get &ldquo;Refresh token&rdquo; and &ldquo;Access token&rdquo;. Okay now let&rsquo;s do some coding 👨&zwj;💻
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<li dir="ltr" style="font-size: 14pt; text-align: left;" aria-level="1">
Create a project Go to your preferred terminal and run: 
<pre class="language-markup" style="font-size: 11pt;"><code>npm init -y</code></pre>
 This command will initialize your node project and create package.json for you. Install necessary packages:&nbsp; 
<pre class="language-markup" style="font-size: 11pt;"><code>npm install nodemailer googleapis</code></pre>
 "googleapis" package is required to authenticate and authorize. 
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<li dir="ltr" style="font-size: 14pt; text-align: left;" aria-level="1">
Create env file and paste the credentials like following:
<pre class="language-markup" style="font-size: 11pt;"><code>GOOGLE_PLAYGROUND_REFRESH_TOKEN=&lt;your refresh token&gt;
GOOGLE_APP_CLIENT_ID=&lt;your client id&gt;
GOOGLE_APP_CLIENT_SECRET=&lt;your client secret&gt;
GOOGLE_PLAYGROUND_REDIRECT_URI=https://developers.google.com/oauthplayground
</code></pre>
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</li>
<li dir="ltr" style="font-size: 14pt; text-align: left;" aria-level="1">
For better read, I&rsquo;ve created a config file:
<pre class="language-javascript" style="font-size: 11pt;"><code>// config.js in root directory

require("dotenv").config();

const GOOGLE_PLAYGROUND_REFRESH_TOKEN =
 process.env.GOOGLE_PLAYGROUND_REFRESH_TOKEN;
const GOOGLE_APP_CLIENT_ID = process.env.GOOGLE_APP_CLIENT_ID;
const GOOGLE_APP_CLIENT_SECRET = process.env.GOOGLE_APP_CLIENT_SECRET;

module.exports = {
 GOOGLE_PLAYGROUND_REFRESH_TOKEN,
 GOOGLE_APP_CLIENT_ID,
 GOOGLE_APP_CLIENT_SECRET,
};
</code></pre>
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</li>
<li dir="ltr" style="font-size: 14pt; text-align: left;" aria-level="1">
Next, I&rsquo;m creating a src/service directory and new file inside service directory From root directory, run the following commands:
<pre class="language-markup" style="font-size: 11pt;"><code>mkdir -p src/service
touch src/service/nodemailer.js</code></pre>
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</li>
<li dir="ltr" style="font-size: 14pt; text-align: left;" aria-level="1">
Open the nodemailer.js file and paste the following code:
<pre class="language-javascript" style="font-size: 11pt;"><code>const nodemailer = require("nodemailer");
const { google } = require("googleapis");

const {
 GOOGLE_PLAYGROUND_REDIRECT_URI,
 GOOGLE_APP_CLIENT_ID,
 GOOGLE_APP_CLIENT_SECRET,
 GOOGLE_PLAYGROUND_REFRESH_TOKEN,
} = require("../config");

async function initiateTransporter(user) {
 try {
 const oAuth2client = new google.auth.OAuth2(
 GOOGLE_APP_CLIENT_ID,
 GOOGLE_APP_CLIENT_SECRET,
 GOOGLE_PLAYGROUND_REDIRECT_URI
 );
 oAuth2client.setCredentials({
 refresh_token: GOOGLE_PLAYGROUND_REFRESH_TOKEN,
 });

 const transporter = nodemailer.createTransport({
 service: "gmail",
 auth: {
 type: "OAuth2",
 user,
 clientId: GOOGLE_APP_CLIENT_ID,
 clientSecret: GOOGLE_APP_CLIENT_SECRET,
 refreshToken: GOOGLE_PLAYGROUND_REFRESH_TOKEN,
 },
 });

 return transporter;
 } catch (err) {
 console.log("Error while initiating transporter");
 console.log(err);
 }
}

module.exports = { initiateTransporter };
</code></pre>
 As you can see here, this code simply authenticates and establishes a connection using googleapis. After that there is the invoke of createTransport() function provided by nodemailer. 
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<li dir="ltr" style="font-size: 14pt; text-align: left;" aria-level="1">
Now create another file or function whose main purpose is to send email. Here I&rsquo;ve created an email.js file at the root directory.
<pre class="language-javascript" style="font-size: 11pt;"><code>const { initiateTransporter } = require("./service/nodemailer");

async function emailInitiate() {
 try {
 const yourEmail = "&lt;Your email address&gt;";
 const transporter = await initiateTransporter(yourEmail);

 await transporter.sendMail({
 from: yourEmail,
 to: "&lt;Email address to whom you want to send email&gt;",
 subject: "Nodemailer with OAuth",
 html: "&lt;p&gt;Hello world&lt;/p&gt;",
 attachments: [], // include if any
 });

 console.log("Email sent");
 } catch (err) {
 console.log("Error while sending email");
 }
}

emailInitiate();</code></pre>
&nbsp;
</li>
<li dir="ltr" style="font-size: 14pt; text-align: left;" aria-level="1">
Now lets run following in your terminal:
<pre class="language-markup" style="font-size: 11pt;"><code>node src/email.js</code></pre>
 Output will be displayed after email is sent successfully:
<pre class="language-markup" style="font-size: 11pt;"><code>Email sent</code></pre>
 Happy coding!! 🙂
</li>
</ol>

Email sending feature is a-must in almost every application. Here is the tutorial on how we can send email using nodemailer and OAuth 2.0 🚀🔥 

Hi! I am Sandeep Bajracharya

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