Send Email in Node.js via SMTP (Nodemailer)

Send email from Node.js with Nodemailer and the AhaSend SMTP relay: STARTTLS on port 587, HTML, attachments, env vars and sandbox testing.

Send emails through AhaSend’s SMTP servers using Node.js with Nodemailer, the most popular and feature-rich email library for Node.js. This guide covers everything from basic setup to advanced features like attachments and custom headers.

Why Nodemailer? Node.js doesn’t have built-in SMTP support, but Nodemailer provides a powerful, well-maintained solution with extensive features including HTML emails, attachments, embedded images, and robust error handling.

Prerequisites

Before sending, verify your domain and create an SMTP credential. Use a sandbox credential for these examples so no email is delivered. Keep the username and password in your server’s secret store.

Before you begin, ensure you have:

System Requirements

• Node.js installed on your system (Download Node.js)
• npm or yarn package manager
• Basic knowledge of JavaScript and Node.js

Installation

Install Nodemailer in your Node.js project:

npm

npm install nodemailer

For TypeScript projects, also install type definitions:

TypeScript Support

npm install --save-dev @types/nodemailer

Connection Settings

Setting	Value
EU host	send.ahasend.com
US connection point	send-us.ahasend.com; accepts SMTP and forwards it to the EU
Ports	25, 587 and 2525
Encryption	STARTTLS required on every supported port
Authentication	AUTH PLAIN only after STARTTLS
Username and password	Your SMTP credential, not an API key
Port 465	Implicit TLS is not supported

All message data is stored in the EU. See SMTP limits.

Basic Email Examples

Plain Text Email

const nodemailer = require('nodemailer');

// Create transporter
const transporter = nodemailer.createTransport({
    host: 'send.ahasend.com',
    port: 587,
    requireTLS: true, // Force TLS
    auth: {
        user: 'YOUR_SMTP_USERNAME',
        pass: 'YOUR_SMTP_PASSWORD'
    }
});

// Email options
const mailOptions = {
    from: '"Your Company" <[e-mail]>',
    to: '[e-mail]',
    subject: 'Welcome to our platform!',
    text: 'Thanks for signing up. We\'re excited to have you!'
};

// Send email
transporter.sendMail(mailOptions, (error, info) => {
    if (error) {
        return console.log('Error:', error);
    }
    console.log('Email sent successfully!');
    console.log('Message ID:', info.messageId);
});

Pro Tip: Use connection pooling for bulk emails, always provide both HTML and text versions, and implement proper error handling with retry logic. Start with sandbox mode during development and use environment variables for credentials.

Testing with Sandbox Mode

Use sandbox mode to safely test your Node.js email integration:

Sandbox Test

const nodemailer = require('nodemailer');

const transporter = nodemailer.createTransport({
    host: 'send.ahasend.com',
    port: 587,
    requireTLS: true,
    auth: {
        user: 'YOUR_SMTP_USERNAME',
        pass: 'YOUR_SMTP_PASSWORD'
    }
});

const mailOptions = {
    from: '"Test Sender" <[e-mail]>',
    to: '[e-mail]',
    subject: 'Sandbox Test Email',
    headers: {
        'AhaSend-Sandbox': 'true',
        'AhaSend-Sandbox-Result': 'deliver'
    },
    text: 'This email is sent in sandbox mode for testing.'
};

transporter.sendMail(mailOptions, (error, info) => {
    if (error) {
        return console.log('Error:', error);
    }
    console.log('Sandbox email sent successfully!');
    console.log('Message ID:', info.messageId);
});

Sandbox Benefits: Emails sent in sandbox mode are free, trigger webhooks normally, and never actually deliver to recipients - perfect for development and testing.

Environment Variables & Best Practices

Using Environment Variables

Nodemailer with environment variables

const nodemailer = require('nodemailer');
require('dotenv').config(); // npm install dotenv

for (const name of ['SMTP_USERNAME', 'SMTP_PASSWORD', 'FROM_EMAIL']) {
    if (!process.env[name]) throw new Error(`${name} is required`);
}

const transporter = nodemailer.createTransport({
    host: process.env.SMTP_HOST || 'send.ahasend.com',
    port: parseInt(process.env.SMTP_PORT) || 587,
    requireTLS: true,
    auth: {
        user: process.env.SMTP_USERNAME,
        pass: process.env.SMTP_PASSWORD
    }
});

const mailOptions = {
    from: { name: process.env.FROM_NAME || "Your Company", address: process.env.FROM_EMAIL },
    to: '[e-mail]',
    subject: 'Environment Test',
    text: 'This email uses environment variables for configuration.'
};

transporter.sendMail(mailOptions, (error, info) => {
    if (error) {
        return console.log('Error:', error);
    }
    console.log('Email sent using environment variables!');
});

Resources

Nodemailer Documentation

Official Nodemailer documentation and examples

AhaSend Support

Get help from our engineering team

Related Guides

• Before sending: verify your domain and create an SMTP credential.
• Connection and message rules: SMTP hosts, ports and limits, special headers, sandbox mode, retention and plan features.
• Other ways to send: REST API, AhaSend CLI, Node.js SDK and Go SDK.
• Delivery events: webhook setup and local webhook testing.