Nodemailer Deployment and Usage Guide

Prerequisites

• Node.js: Version 6.0.0 or higher (required for spread operator support)
• Package Manager: npm (comes with Node.js)
• Email Service: Access to an SMTP server (e.g., Gmail, Outlook, custom SMTP)
• Network: Ability to make outbound connections on SMTP ports (25, 465, 587)

Installation

Using npm (Recommended)

npm install nodemailer

Manual Installation

1. Clone the repository:

git clone https://github.com/nodemailer/nodemailer.git
cd nodemailer

2. Install dependencies:

npm install

Configuration

Basic SMTP Configuration

const nodemailer = require('nodemailer');

let transporter = nodemailer.createTransport({
    host: 'smtp.example.com',
    port: 587,
    secure: false, // true for port 465, false for port 587
    auth: {
        user: 'username@example.com',
        pass: 'password'
    }
});

Environment Variables

For production, use environment variables:

export SMTP_HOST=smtp.example.com
export SMTP_PORT=587
export SMTP_USER=username@example.com
export SMTP_PASS=password

TLS Configuration

let transporter = nodemailer.createTransport({
    host: 'smtp.example.com',
    port: 587,
    secure: false,
    tls: {
        rejectUnauthorized: true,
        minVersion: 'TLSv1.2'
    },
    auth: {
        user: process.env.SMTP_USER,
        pass: process.env.SMTP_PASS
    }
});

Build & Run

Development

# Run tests
npm test

# Run linting
npm run lint

# Start development server
npm run dev

Sending Emails

const nodemailer = require('nodemailer');

// Create transporter
let transporter = nodemailer.createTransport({
    host: 'smtp.example.com',
    port: 587,
    secure: false,
    auth: {
        user: 'username@example.com',
        pass: 'password'
    }
});

// Send email
transporter.sendMail({
    from: 'sender@example.com',
    to: 'receiver@example.com',
    subject: 'Hello',
    text: 'Hello world',
    html: '<b>Hello world</b>'
}).then(info => {
    console.log('Message sent: %s', info.messageId);
}).catch(err => {
    console.error('Error sending email:', err);
});

Production

# Build for production
npm run build

# Start production server
npm start

Deployment

Platform Options

1. Heroku

# Deploy to Heroku
git push heroku main

2. AWS Lambda

// Lambda handler example
exports.handler = async (event) => {
    const transporter = nodemailer.createTransport({
        host: process.env.SMTP_HOST,
        port: process.env.SMTP_PORT,
        secure: false,
        auth: {
            user: process.env.SMTP_USER,
            pass: process.env.SMTP_PASS
        }
    });

    // Send email logic
};

3. Docker

# Dockerfile
FROM node:18-alpine
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
EXPOSE 3000
CMD ["npm", "start"]

Environment Variables for Production

# SMTP Configuration
SMTP_HOST=smtp.gmail.com
SMTP_PORT=587
SMTP_USER=your-email@gmail.com
SMTP_PASS=your-app-password

# Security
NODE_ENV=production

Troubleshooting

Common Issues and Solutions

1. ETIMEDOUT Errors

# Check firewall settings
# Allow outbound connections on SMTP ports

2. Gmail Issues

// Use App Password instead of regular password
// Enable "Less secure app access" in Gmail settings

3. TLS Errors

// Update Node.js to latest version
// Set correct TLS version
let transporter = nodemailer.createTransport({
    host: 'smtp.example.com',
    port: 587,
    secure: false,
    tls: {
        rejectUnauthorized: true,
        minVersion: 'TLSv1.2'
    }
});

4. DNS Resolution Issues

// Use IP address instead of hostname
let transporter = nodemailer.createTransport({
    host: '1.2.3.4', // IP address
    port: 465,
    secure: true,
    tls: {
        servername: 'example.com'
    }
});

5. SyntaxError for "..."

# Upgrade Node.js to version 6.0.0 or higher

6. Rate Limiting

// Configure rate limits
let transporter = nodemailer.createTransport({
    rateDelta: 1000, // 1 second
    rateLimit: 5 // 5 emails per second
});

Debug Mode

// Enable debug logging
process.env.DEBUG = 'nodemailer:*';

// Or in code
nodemailer.createTestAccount((err, account) => {
    console.log('Credentials obtained, sending message...');
});

Performance Tips

1. Use Connection Pooling:

let transporter = nodemailer.createTransport({
    pool: true,
    maxConnections: 5,
    maxMessages: 100
});

2. Enable Compression:

let transporter = nodemailer.createTransport({
    compression: true
});

3. Use Environment Variables for sensitive data in production.