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Node.js Send an Email - Complete Email Implementation Guide

Sending emails is a common requirement in web applications for notifications, confirmations, newsletters, and more. Node.js provides several libraries and methods to implement email functionality effectively.

Email Libraries for Node.js​

  1. Nodemailer - Most popular and feature-rich
  2. EmailJS - Client-side email sending
  3. SendGrid - Cloud-based email service
  4. Mailgun - Transactional email service
  5. AWS SES - Amazon Simple Email Service

Using Nodemailer​

Installation​

npm install nodemailer

Basic Email Setup​

const nodemailer = require('nodemailer');

// Create transporter
const transporter = nodemailer.createTransporter({
  service: 'gmail',
  auth: {
    user: '[email protected]',
    pass: 'your-app-password' // Use App Password for Gmail
  }
});

// Email options
const mailOptions = {
  from: '[email protected]',
  to: '[email protected]',
  subject: 'Test Email',
  text: 'This is a test email from Node.js'
};

// Send email
transporter.sendMail(mailOptions, (error, info) => {
  if (error) {
    console.error('Error:', error);
  } else {
    console.log('Email sent:', info.response);
  }
});

SMTP Configuration​

const nodemailer = require('nodemailer');

// SMTP configuration
const transporter = nodemailer.createTransporter({
  host: 'smtp.gmail.com',
  port: 587,
  secure: false, // true for 465, false for other ports
  auth: {
    user: '[email protected]',
    pass: 'your-app-password'
  },
  tls: {
    rejectUnauthorized: false
  }
});

// Alternative SMTP configurations
const gmailConfig = {
  service: 'gmail',
  auth: {
    user: '[email protected]',
    pass: 'your-app-password'
  }
};

const outlookConfig = {
  host: 'smtp-mail.outlook.com',
  port: 587,
  secure: false,
  auth: {
    user: '[email protected]',
    pass: 'your-password'
  }
};

const yahooConfig = {
  host: 'smtp.mail.yahoo.com',
  port: 587,
  secure: false,
  auth: {
    user: '[email protected]',
    pass: 'your-app-password'
  }
};

HTML Emails​

Basic HTML Email​

const nodemailer = require('nodemailer');

const transporter = nodemailer.createTransporter({
  service: 'gmail',
  auth: {
    user: '[email protected]',
    pass: 'your-app-password'
  }
});

const mailOptions = {
  from: '[email protected]',
  to: '[email protected]',
  subject: 'Welcome to Our Service',
  html: `
    <!DOCTYPE html>
    <html>
    <head>
      <style>
        body { font-family: Arial, sans-serif; line-height: 1.6; color: #333; }
        .container { max-width: 600px; margin: 0 auto; padding: 20px; }
        .header { background: #007acc; color: white; padding: 20px; text-align: center; }
        .content { padding: 20px; background: #f9f9f9; }
        .button { display: inline-block; padding: 10px 20px; background: #007acc; color: white; text-decoration: none; border-radius: 5px; }
        .footer { text-align: center; padding: 20px; color: #666; font-size: 12px; }
      </style>
    </head>
    <body>
      <div class="container">
        <div class="header">
          <h1>Welcome to Our Service!</h1>
        </div>
        <div class="content">
          <h2>Hello there!</h2>
          <p>Thank you for signing up for our service. We're excited to have you on board!</p>
          <p>Here's what you can do next:</p>
          <ul>
            <li>Complete your profile</li>
            <li>Explore our features</li>
            <li>Connect with other users</li>
          </ul>
          <p style="text-align: center;">
            <a href="https://example.com/dashboard" class="button">Get Started</a>
          </p>
        </div>
        <div class="footer">
          <p>© 2024 Our Company. All rights reserved.</p>
          <p>If you didn't sign up for this service, please ignore this email.</p>
        </div>
      </div>
    </body>
    </html>
  `
};

transporter.sendMail(mailOptions, (error, info) => {
  if (error) {
    console.error('Error:', error);
  } else {
    console.log('Email sent:', info.response);
  }
});

Email Templates​

// Email template function
function createWelcomeEmail(user) {
  return `
    <!DOCTYPE html>
    <html>
    <head>
      <style>
        body { font-family: Arial, sans-serif; line-height: 1.6; color: #333; }
        .container { max-width: 600px; margin: 0 auto; padding: 20px; }
        .header { background: #007acc; color: white; padding: 20px; text-align: center; }
        .content { padding: 20px; background: #f9f9f9; }
        .button { display: inline-block; padding: 10px 20px; background: #007acc; color: white; text-decoration: none; border-radius: 5px; }
        .footer { text-align: center; padding: 20px; color: #666; font-size: 12px; }
      </style>
    </head>
    <body>
      <div class="container">
        <div class="header">
          <h1>Welcome ${user.name}!</h1>
        </div>
        <div class="content">
          <h2>Hello ${user.name}!</h2>
          <p>Thank you for signing up for our service. We're excited to have you on board!</p>
          <p>Your account details:</p>
          <ul>
            <li><strong>Email:</strong> ${user.email}</li>
            <li><strong>Username:</strong> ${user.username}</li>
            <li><strong>Signup Date:</strong> ${new Date().toLocaleDateString()}</li>
          </ul>
          <p style="text-align: center;">
            <a href="https://example.com/dashboard" class="button">Access Your Dashboard</a>
          </p>
        </div>
        <div class="footer">
          <p>© 2024 Our Company. All rights reserved.</p>
        </div>
      </div>
    </body>
    </html>
  `;
}

// Usage
const user = {
  name: 'John Doe',
  email: '[email protected]',
  username: 'johndoe'
};

const mailOptions = {
  from: '[email protected]',
  to: user.email,
  subject: 'Welcome to Our Service!',
  html: createWelcomeEmail(user)
};

Email with Attachments​

File Attachments​

const nodemailer = require('nodemailer');
const path = require('path');

const transporter = nodemailer.createTransporter({
  service: 'gmail',
  auth: {
    user: '[email protected]',
    pass: 'your-app-password'
  }
});

const mailOptions = {
  from: '[email protected]',
  to: '[email protected]',
  subject: 'Email with Attachments',
  text: 'Please find the attached files.',
  attachments: [
    {
      filename: 'document.pdf',
      path: './uploads/document.pdf'
    },
    {
      filename: 'image.jpg',
      path: './uploads/image.jpg',
      cid: 'unique-image-id' // For inline images
    },
    {
      filename: 'data.txt',
      content: 'This is the content of the file',
      contentType: 'text/plain'
    }
  ]
};

transporter.sendMail(mailOptions, (error, info) => {
  if (error) {
    console.error('Error:', error);
  } else {
    console.log('Email sent:', info.response);
  }
});

Inline Images​

const mailOptions = {
  from: '[email protected]',
  to: '[email protected]',
  subject: 'Email with Inline Images',
  html: `
    <h1>Hello!</h1>
    <p>Here's an inline image:</p>
    <img src="cid:unique-image-id" alt="Inline Image" style="max-width: 100%;">
    <p>Best regards,<br>Your Team</p>
  `,
  attachments: [
    {
      filename: 'logo.png',
      path: './images/logo.png',
      cid: 'unique-image-id'
    }
  ]
};

Email Service Integration​

SendGrid Integration​

npm install @sendgrid/mail
const sgMail = require('@sendgrid/mail');

// Set API key
sgMail.setApiKey(process.env.SENDGRID_API_KEY);

const msg = {
  to: '[email protected]',
  from: '[email protected]',
  subject: 'Hello from SendGrid',
  text: 'Hello from SendGrid!',
  html: '<strong>Hello from SendGrid!</strong>'
};

sgMail.send(msg)
  .then(() => {
    console.log('Email sent');
  })
  .catch((error) => {
    console.error('Error:', error);
  });

Mailgun Integration​

npm install mailgun-js
const mailgun = require('mailgun-js')({
  apiKey: process.env.MAILGUN_API_KEY,
  domain: process.env.MAILGUN_DOMAIN
});

const data = {
  from: '[email protected]',
  to: '[email protected]',
  subject: 'Hello from Mailgun',
  text: 'Hello from Mailgun!',
  html: '<strong>Hello from Mailgun!</strong>'
};

mailgun.messages().send(data, (error, body) => {
  if (error) {
    console.error('Error:', error);
  } else {
    console.log('Email sent:', body);
  }
});

AWS SES Integration​

npm install aws-sdk
const AWS = require('aws-sdk');

// Configure AWS SES
const ses = new AWS.SES({
  region: 'us-east-1',
  accessKeyId: process.env.AWS_ACCESS_KEY_ID,
  secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY
});

const params = {
  Destination: {
    ToAddresses: ['[email protected]']
  },
  Message: {
    Body: {
      Html: {
        Data: '<h1>Hello from AWS SES!</h1>',
        Charset: 'UTF-8'
      },
      Text: {
        Data: 'Hello from AWS SES!',
        Charset: 'UTF-8'
      }
    },
    Subject: {
      Data: 'Hello from AWS SES',
      Charset: 'UTF-8'
    }
  },
  Source: '[email protected]'
};

ses.sendEmail(params, (error, data) => {
  if (error) {
    console.error('Error:', error);
  } else {
    console.log('Email sent:', data);
  }
});

Complete Email Service​

Email Service Class​

const nodemailer = require('nodemailer');
const path = require('path');

class EmailService {
  constructor() {
    this.transporter = nodemailer.createTransporter({
      service: 'gmail',
      auth: {
        user: process.env.EMAIL_USER,
        pass: process.env.EMAIL_PASS
      }
    });
  }

  // Send welcome email
  async sendWelcomeEmail(user) {
    const mailOptions = {
      from: process.env.EMAIL_USER,
      to: user.email,
      subject: 'Welcome to Our Service!',
      html: this.createWelcomeTemplate(user)
    };

    try {
      const info = await this.transporter.sendMail(mailOptions);
      console.log('Welcome email sent:', info.messageId);
      return { success: true, messageId: info.messageId };
    } catch (error) {
      console.error('Error sending welcome email:', error);
      return { success: false, error: error.message };
    }
  }

  // Send password reset email
  async sendPasswordResetEmail(user, resetToken) {
    const resetUrl = `${process.env.FRONTEND_URL}/reset-password?token=${resetToken}`;
    
    const mailOptions = {
      from: process.env.EMAIL_USER,
      to: user.email,
      subject: 'Password Reset Request',
      html: this.createPasswordResetTemplate(user, resetUrl)
    };

    try {
      const info = await this.transporter.sendMail(mailOptions);
      console.log('Password reset email sent:', info.messageId);
      return { success: true, messageId: info.messageId };
    } catch (error) {
      console.error('Error sending password reset email:', error);
      return { success: false, error: error.message };
    }
  }

  // Send notification email
  async sendNotificationEmail(user, notification) {
    const mailOptions = {
      from: process.env.EMAIL_USER,
      to: user.email,
      subject: notification.subject,
      html: this.createNotificationTemplate(user, notification)
    };

    try {
      const info = await this.transporter.sendMail(mailOptions);
      console.log('Notification email sent:', info.messageId);
      return { success: true, messageId: info.messageId };
    } catch (error) {
      console.error('Error sending notification email:', error);
      return { success: false, error: error.message };
    }
  }

  // Send email with attachment
  async sendEmailWithAttachment(recipient, subject, content, attachmentPath) {
    const mailOptions = {
      from: process.env.EMAIL_USER,
      to: recipient,
      subject: subject,
      html: content,
      attachments: [
        {
          filename: path.basename(attachmentPath),
          path: attachmentPath
        }
      ]
    };

    try {
      const info = await this.transporter.sendMail(mailOptions);
      console.log('Email with attachment sent:', info.messageId);
      return { success: true, messageId: info.messageId };
    } catch (error) {
      console.error('Error sending email with attachment:', error);
      return { success: false, error: error.message };
    }
  }

  // Template methods
  createWelcomeTemplate(user) {
    return `
      <!DOCTYPE html>
      <html>
      <head>
        <style>
          body { font-family: Arial, sans-serif; line-height: 1.6; color: #333; }
          .container { max-width: 600px; margin: 0 auto; padding: 20px; }
          .header { background: #007acc; color: white; padding: 20px; text-align: center; }
          .content { padding: 20px; background: #f9f9f9; }
          .button { display: inline-block; padding: 10px 20px; background: #007acc; color: white; text-decoration: none; border-radius: 5px; }
          .footer { text-align: center; padding: 20px; color: #666; font-size: 12px; }
        </style>
      </head>
      <body>
        <div class="container">
          <div class="header">
            <h1>Welcome ${user.name}!</h1>
          </div>
          <div class="content">
            <h2>Hello ${user.name}!</h2>
            <p>Thank you for signing up for our service. We're excited to have you on board!</p>
            <p style="text-align: center;">
              <a href="${process.env.FRONTEND_URL}/dashboard" class="button">Access Your Dashboard</a>
            </p>
          </div>
          <div class="footer">
            <p>© 2024 Our Company. All rights reserved.</p>
          </div>
        </div>
      </body>
      </html>
    `;
  }

  createPasswordResetTemplate(user, resetUrl) {
    return `
      <!DOCTYPE html>
      <html>
      <head>
        <style>
          body { font-family: Arial, sans-serif; line-height: 1.6; color: #333; }
          .container { max-width: 600px; margin: 0 auto; padding: 20px; }
          .header { background: #dc3545; color: white; padding: 20px; text-align: center; }
          .content { padding: 20px; background: #f9f9f9; }
          .button { display: inline-block; padding: 10px 20px; background: #dc3545; color: white; text-decoration: none; border-radius: 5px; }
          .footer { text-align: center; padding: 20px; color: #666; font-size: 12px; }
        </style>
      </head>
      <body>
        <div class="container">
          <div class="header">
            <h1>Password Reset Request</h1>
          </div>
          <div class="content">
            <h2>Hello ${user.name}!</h2>
            <p>You requested a password reset for your account.</p>
            <p>Click the button below to reset your password:</p>
            <p style="text-align: center;">
              <a href="${resetUrl}" class="button">Reset Password</a>
            </p>
            <p><strong>Note:</strong> This link will expire in 1 hour.</p>
          </div>
          <div class="footer">
            <p>© 2024 Our Company. All rights reserved.</p>
            <p>If you didn't request this, please ignore this email.</p>
          </div>
        </div>
      </body>
      </html>
    `;
  }

  createNotificationTemplate(user, notification) {
    return `
      <!DOCTYPE html>
      <html>
      <head>
        <style>
          body { font-family: Arial, sans-serif; line-height: 1.6; color: #333; }
          .container { max-width: 600px; margin: 0 auto; padding: 20px; }
          .header { background: #28a745; color: white; padding: 20px; text-align: center; }
          .content { padding: 20px; background: #f9f9f9; }
          .footer { text-align: center; padding: 20px; color: #666; font-size: 12px; }
        </style>
      </head>
      <body>
        <div class="container">
          <div class="header">
            <h1>${notification.subject}</h1>
          </div>
          <div class="content">
            <h2>Hello ${user.name}!</h2>
            <p>${notification.message}</p>
          </div>
          <div class="footer">
            <p>© 2024 Our Company. All rights reserved.</p>
          </div>
        </div>
      </body>
      </html>
    `;
  }
}

module.exports = EmailService;

Express Route Integration​

const express = require('express');
const EmailService = require('./EmailService');

const app = express();
const emailService = new EmailService();

// Middleware
app.use(express.json());

// Send welcome email
app.post('/send-welcome', async (req, res) => {
  try {
    const { user } = req.body;
    const result = await emailService.sendWelcomeEmail(user);
    
    if (result.success) {
      res.json({ message: 'Welcome email sent successfully' });
    } else {
      res.status(500).json({ error: result.error });
    }
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

// Send password reset email
app.post('/send-password-reset', async (req, res) => {
  try {
    const { user, resetToken } = req.body;
    const result = await emailService.sendPasswordResetEmail(user, resetToken);
    
    if (result.success) {
      res.json({ message: 'Password reset email sent successfully' });
    } else {
      res.status(500).json({ error: result.error });
    }
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

// Send notification email
app.post('/send-notification', async (req, res) => {
  try {
    const { user, notification } = req.body;
    const result = await emailService.sendNotificationEmail(user, notification);
    
    if (result.success) {
      res.json({ message: 'Notification email sent successfully' });
    } else {
      res.status(500).json({ error: result.error });
    }
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
  console.log(`Server running on port ${PORT}`);
});

Email Queue System​

Using Bull Queue​

npm install bull
const Queue = require('bull');
const EmailService = require('./EmailService');

// Create email queue
const emailQueue = new Queue('email processing', {
  redis: {
    host: 'localhost',
    port: 6379
  }
});

const emailService = new EmailService();

// Process email jobs
emailQueue.process('send-welcome', async (job) => {
  const { user } = job.data;
  return await emailService.sendWelcomeEmail(user);
});

emailQueue.process('send-password-reset', async (job) => {
  const { user, resetToken } = job.data;
  return await emailService.sendPasswordResetEmail(user, resetToken);
});

// Add email to queue
async function queueWelcomeEmail(user) {
  await emailQueue.add('send-welcome', { user }, {
    delay: 1000, // 1 second delay
    attempts: 3, // Retry 3 times
    backoff: 'exponential'
  });
}

async function queuePasswordResetEmail(user, resetToken) {
  await emailQueue.add('send-password-reset', { user, resetToken }, {
    delay: 500, // 500ms delay
    attempts: 2
  });
}

module.exports = { emailQueue, queueWelcomeEmail, queuePasswordResetEmail };

Best Practices​

1. Environment Variables​

# .env
EMAIL_USER=[email protected]
EMAIL_PASS=your-app-password
SENDGRID_API_KEY=your-sendgrid-api-key
MAILGUN_API_KEY=your-mailgun-api-key
MAILGUN_DOMAIN=your-mailgun-domain
FRONTEND_URL=http://localhost:3000

2. Error Handling​

const sendEmail = async (mailOptions) => {
  try {
    const info = await transporter.sendMail(mailOptions);
    return { success: true, messageId: info.messageId };
  } catch (error) {
    console.error('Email error:', error);
    
    // Handle specific errors
    if (error.code === 'EAUTH') {
      return { success: false, error: 'Authentication failed' };
    } else if (error.code === 'ECONNECTION') {
      return { success: false, error: 'Connection failed' };
    } else {
      return { success: false, error: 'Unknown error occurred' };
    }
  }
};

3. Rate Limiting​

const rateLimit = require('express-rate-limit');

const emailRateLimit = rateLimit({
  windowMs: 15 * 60 * 1000, // 15 minutes
  max: 5, // limit each IP to 5 requests per windowMs
  message: 'Too many email requests, please try again later'
});

app.use('/send-email', emailRateLimit);

4. Email Validation​

const validator = require('validator');

const validateEmail = (email) => {
  return validator.isEmail(email);
};

const sendEmail = async (recipient, subject, content) => {
  if (!validateEmail(recipient)) {
    throw new Error('Invalid email address');
  }
  
  // Send email logic
};

Next Steps​

Now that you understand email functionality, you're ready to:

  1. Node.js - Events - Learn event-driven programming
  2. Node.js - Event Loop - Understand the event loop
  3. Node.js - Event Emitter - Learn custom event handling
  4. Node.js - Debugger - Master debugging techniques

Email Mastery Complete! You now know how to implement comprehensive email functionality in Node.js applications. Email is essential for user communication and notifications!