Skip to main content

​
Overview

Nuntly provides an SMTP server that allows you to send emails using standard SMTP clients and libraries. This is perfect if you want to integrate email sending into existing applications or use tools that support SMTP.

​
SMTP Configuration

Use these settings to configure your SMTP client:
SettingValue
Hostsmtp.nuntly.com
Port587
Usernamenuntly
PasswordYour Nuntly API Key (starts with ntly_)
You need a valid API key to authenticate with the SMTP server. You can create one in the API Keys section of your dashboard. The from address must belong to a verified domain in your account.

​
Understanding SMTP Ports

Nuntly SMTP server uses port 587 with STARTTLS encryption. Here’s what you need to know about SMTP ports:
PortSecurityDescriptionNuntly Support
25NoneStandard SMTP port, often blocked by ISPs❌ Not supported
465SSL/TLSSMTP over implicit SSL❌ Not supported
587STARTTLSModern SMTP submission with opportunistic encryption✅ Recommended
2525STARTTLSAlternative submission port (for restrictive networks)❌ Not supported
Why port 587?
Port 587 is the standard port for email submission (RFC 6409) and uses STARTTLS to upgrade the connection to encrypted. This provides better compatibility and security than older approaches.

​
Code Examples

Each example below configures an SMTP client with your Nuntly credentials, composes a message with both plain text and HTML parts, and sends it through the Nuntly SMTP server. Simply replace ntly_your_api_key_here with your actual API key. 
const nodemailer = require('nodemailer');

const transporter = nodemailer.createTransport({
host: 'smtp.nuntly.com',
port: 587,
secure: false, // Use STARTTLS
auth: {
user: 'nuntly',
pass: 'ntly_your_api_key_here',
},
});

const mailOptions = {
from: 'ray@info.tomlinson.ai',
to: 'maiya5@gmail.com',
subject: 'Hello from Nuntly SMTP',
text: 'This is a test email sent via SMTP',
html: '<h1>Hello!</h1><p>This is a test email sent via SMTP</p>',
};

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

​
Shell (Swaks)

Swaks (Swiss Army Knife for SMTP) is a powerful command-line tool for testing SMTP servers. The examples below cover sending a plain text email, an HTML email, and a verbose connection test, all from the terminal. Install Swaks 
brew install swaks
Send a simple email 
swaks --to maiya5@gmail.com \
      --from ray@info.tomlinson.ai \
      --server smtp.nuntly.com:587 \
      --auth LOGIN \
      --auth-user nuntly \
      --auth-password ntly_your_api_key_here \
      --tls \
      --header "Subject: Hello from Swaks" \
      --body "This is a test email sent via Swaks"
Send an HTML email: 
swaks --to maiya5@gmail.com \
      --from ray@info.tomlinson.ai \
      --server smtp.nuntly.com:587 \
      --auth LOGIN \
      --auth-user nuntly \
      --auth-password ntly_your_api_key_here \
      --tls \
      --header "Subject: Hello from Swaks" \
      --header "Content-Type: text/html" \
      --body '<h1>Hello!</h1><p>This is a test email sent via Swaks</p>'
Test SMTP connection (with verbose output): 
swaks --to maiya5@gmail.com \
      --from ray@info.tomlinson.ai \
      --server smtp.nuntly.com:587 \
      --auth LOGIN \
      --auth-user nuntly \
      --auth-password ntly_your_api_key_here \
      --tls \
      --header "Subject: SMTP Connection Test" \
      --body "Testing SMTP connectivity" \
      --show-password
Use the --show-password flag to display the full SMTP conversation, including authentication. This is useful for debugging connection issues.

​
Troubleshooting

​
Authentication Failed

Make sure you’re using:
  • Username: exactly nuntly (lowercase)
  • Password: Your valid API key (starts with ntly_)

​
Connection Timeout

Verify that:
  • Port 587 is not blocked by your firewall
  • You’re using STARTTLS (not SSL/TLS)
  • The SMTP server hostname is correct: smtp.nuntly.com

​
Email Size Exceeded

If you receive a “552 Email size exceeds limit” error:
  • Reduce your email size
  • Upload large files to a blob storage (e.g. AWS S3, Google Cloud Storage, Azure Blob) and include a download link in the email body instead of attaching them

​
Learn more

Handle webhook events

Receive and process delivery, bounce, and open events in your app

API Reference

Explore the REST API for advanced features