Node.js + Nodemailer : How to send Emails via SMTP with Nodemailer

Nodemailer is a Node.js package that makes sending emails as simple as pie. The project began in 2010 when there was no logical way to send email messages, and it is now the default solution for most Node.js users.

This article aims to demonstrate and explain how to send emails via SMTP with Nodemailer.

In short, to send messages via SMTP using Nodemailer, you will need to follow these steps:

1. Download and Install Nodemailer Module.
2. Create Nodemailer transporter using SMTP.
3. Setting up the smtpOptions object.
4. Setting up mail options (mailOptions object).
5. Deliver the mailOptions using the sendMail() method.
6. Test emails using Mailtrap.
7. Test emails using Ethereal.
8. Sending emails using a Gmail account.

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Step1: Install Nodemailer Module

To get started with Nodemailer, you need Node.js version 6.0 or higher. All public Nodemailer functions support callbacks and Promises but if you wish to use async..await with Nodemailer, you will need at least Node v8.0.0.
You should also download and install it using yarn or npm:

 yarn add nodemailer

 >npm install --save nodemailer

The next step is to include the module in our application by adding the following line of code:

  const nodemailer = require('nodemailer');

Now we are ready to use Nodemailer. We will create the transporter in the following sections and configure the mail message.

Step2: Create Nodemailer transporter using  SMTP 

SMTP is the most common transport mechanism in Nodemailer. It is a protocol that connects various email hosts because everything is relatively essential with SMTP, all you have to do is set the host, port, authentication information, and method, and you are done. One of the advantages of using SMTP is that if you need to replace one provider with another, you only need to change the configuration options mentioned previously.

You must first set up a transport mechanism before sending any emails. This may be accomplished using a nodemailer. createTransport(type, options), where type is the transport mechanism (in our case SMTP) and options define the connection data and how it will be used.

 
 const  transport = nodemailer.createTransport("SMTP", {smtpOptions});

To create the reusable transporter object using the default SMTP transport, you can use:

 
 const  transport = nodemailer.createTransport({smtpOptions});

It is also good to double-check that the SMTP connection is working correctly. You can use the verify(callback) method to validate the connection and authentication.

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

Remember that this callback simply checks for connection and authentication; it does not determine whether or not the service permits you to use a specific envelope From the address.

Step3: Setting up the smtpOptions

smtpOptions is an object that contains all the data related to the connection and the security parameters. The SMTP options can be divided into seven categories:

Example of smtpOptions:

The following example is the smtpOptions that we used in our forgot/reset password tutorial to send a forgot password message to the user. You can check this article here: Add Forgot/Reset Password to Login-Authentication System.

Furthermore, there is a complete example of how to send email using a Gmail account here: Nodemailer + Gmail: How to Send Emails from Node.js API using Gmail.

The authentication type used in the following example is ‘login’ for an ethereal account and the options object:{

user is the username

pass is the password for the user

 }

 const transporter = nodemailer.createTransport({
            host: 'smtp.ethereal.email',
            port: 587,
            auth: {
              user: process.env.USER, 
              pass: process.env.PASS 
            }
    })

Step4: Setting up mail options (mailOptions object)

The mailOptions object is used to precisely define who sends what to whom, and The following table resumes all the fields in five categories. We are not supposed to use all these options while sending a message; most the developers use only a few from the basic fields.

Example of mailOptions:

The following example is the mailOptions that we used in our forgot/reset password tutorial to send forgot password message to the user. You can check this article here: Add Forgot/Reset Password to Login-Authentication System.

  
 let  message = `<p>Please use the below token to reset your password with the <code>/apiRouter/reset-password</code> api route:</p>
                       <p><code>${resetToken}</code></p>`; // Here you can replace the message with your HTML code.

  const  mailOptions = {
    from: process.env.EMAIL_FROM,
    to: email, // the user email
    subject: ' Reset your Password',
    html: `<h4>Reset Password</h4>
                   ${message}`
   };

Step5: Deliver the mailOptions using the sendMail()

In the sections above, we created a reusable Nodemailer transporter using the SMTP transport mechanism, and we set up the mailOptions object. In this section, we will send the message object using the sendMailer() method of the defined SMTP transporter.

Example of using sendMail() :

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

Nodemailer Example:

  const nodemailer = require('nodemailer');

  const transporter = nodemailer.createTransport({
            host: 'smtp.ethereal.email',
            port: 587,
            auth: {
              user: process.env.USER, 
              pass: process.env.PASS 
            }
    })


   let  message = `<p>Please use the below token to reset your password with the <code>/apiRouter/reset-password</code> api route:</p>
                       <p><code>${resetToken}</code></p>`; // Here you can replace the message with your HTML code.

  const  mailOptions = {
    from: process.env.EMAIL_FROM,
    to: email, // the user email
    subject: ' Reset your Password',
    html: `<h4>Reset Password</h4>
                   ${message}`
   };



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




   

Test emails in nodemailer using Mailtrap

Mailtrap is an online tool for email testing in a dev environment. It captures SMTP traffic and messages, analyses the content of the emails for spam score, validates HTML/CSS, and then displays how they should look in a real email.

In order to use Mailtrap, we need first to set up an account. You can set up your account for free here: Mailtrap Sign Up.

Then click on My inbox, and then select the SMTP settings tab. Next, click on Integrations and select the Nodemailer integration. Please copy the code and insert it into your application.

The code already contains a transporter and the smtpOptions:

 var transport = nodemailer.createTransport({
  host: "smtp.mailtrap.io",
  port: 2525,
  auth: {
    user: "11ff58c26075fa",
    pass: "1d4f72f480930e"
  }
});

If you want to see a complete example of how to send and test reset password email using nodemailer, check this article: …………..

  
const nodemailer = require('nodemailer');

  const  transport = nodemailer.createTransport({
  host: "smtp.mailtrap.io",
  port: 2525,
  auth: {
    user: "11ff58c26075fa",
    pass: "1d4f72f480930e"
  }
});


   let  message = `<p>Please use the below token to reset your password with the <code>/apiRouter/reset-password</code> api route:</p>
                       <p><code>${resetToken}</code></p>`; // Here you can replace the message with your HTML code.

  const  mailOptions = {
    from: process.env.EMAIL_FROM,
    to: email, // the user email
    subject: ' Reset your Password',
    html: `<h4>Reset Password</h4>
                   ${message}`
   };



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




  

Test emails in nodemailer using Ethereal

Ethereal is a fake SMTP service used to auto-generate email test accounts.

You can generate an email account from Nodemailer using the following line of code:

 
 let testAccount = await nodemailer.createTestAccount();

Or create an account here: create Ethereal account.

Ethereal account:

To send an email using that account, all you have to do is copy the code in the Nodemailer configuration section and insert it into your application.
If you want to check your mailbox, click on Open Mailbox.
If you want to see a complete example of how to send and test reset password email using nodemailer, check this article: …………..

  const transporter = nodemailer.createTransport({
    host: 'smtp.ethereal.email',
    port: 587,
    auth: {
        user: '[email protected]',
        pass: 'E8QVyfKbNut785cMKY'
    }
});

  
const nodemailer = require('nodemailer');

  const transporter = nodemailer.createTransport({
    host: 'smtp.ethereal.email',
    port: 587,
    auth: {
        user: '[email protected]',
        pass: 'E8QVyfKbNut785cMKY'
    }
});


   let  message = `<p>Please use the below token to reset your password with the <code>/apiRouter/reset-password</code> api route:</p>
                       <p><code>${resetToken}</code></p>`; // Here you can replace the message with your HTML code.

  const  mailOptions = {
    from: process.env.EMAIL_FROM,
    to: email, // the user email
    subject: ' Reset your Password',
    html: `<h4>Reset Password</h4>
                   ${message}`
   };



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




  

Conclusion

In this article, we explained and demonstrated how to create and send emails from a node.js API using Nodemailer via an SMTP service, and we gave two ways to test emails: Mailtrap and Ethereal. Hope this was helpful.

You might also like:

Best practices for optimizing MySQL database performance.

Node.js + MySQL : Add Forgot/Reset Password to Login-Authentication System.

How to add Custom Error Handler Middleware to your Node.js/Express API.

Nodemailer + Gmail: How to Send Emails from Node.js API using Gmail.

Complete JWT Authentication and Authorization System for MySQL/Node.js API.

How to Build a Complete API for User Login and Authentication using MySQL and Node.js.

How to store Session in MySQL Database using express-mysql-session.

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