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.
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.
Nuntly SMTP server uses port 587 with STARTTLS encryption. Here’s what you need to know about SMTP ports:
Port
Security
Description
Nuntly Support
25
None
Standard SMTP port, often blocked by ISPs
❌ Not supported
465
SSL/TLS
SMTP over implicit SSL
❌ Not supported
587
STARTTLS
Modern SMTP submission with opportunistic encryption
✅ Recommended
2525
STARTTLS
Alternative 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.
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.
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const nodemailer = require('nodemailer');const transporter = nodemailer.createTransport({host: 'smtp.nuntly.com',port: 587,secure: false, // Use STARTTLSauth: {user: 'nuntly',pass: 'ntly_your_api_key_here',},});const mailOptions = {from: '[email protected]',to: '[email protected]',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);}});
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
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brew install swaks
Send a simple email
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swaks --to[email protected] \ --from[email protected] \ --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:
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swaks --to[email protected] \ --from[email protected] \ --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>'
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
