Sidemail News (April 2026): SMTP relay with markdown support

We've just released SMTP relay on Sidemail.io! Plus native markdown support.

This is perfect if you have legacy systems or tools that can only send via SMTP (instead of our API).

How to connect

• Host: mx.sidemail.net
• Username: leave empty
• Password: your Sidemail API key

Markdown support

We've also added markdown support. Just add this header to your email:

x-sidemail-markdown: true

How it works

Sidemail will automatically turn your plain text into a clean, branded HTML email using your project's logo, colors, and design settings. No extra work needed on your side.

Full documentation is here: sidemail.io/docs/smtp-relay

Whether you're migrating an old system or just want a simpler way to send, this should make things much easier.

Give it a try and let us know what you think! And if you have any questions, we're happy to help.

Example with Nodemailer

const nodemailer = require("nodemailer");

const transporter = nodemailer.createTransport({
	host: "mx.sidemail.net",
	port: 587,
	secure: false,
	auth: {
		user: "api",
		pass: "your-api-key",
	},
});

await transporter.sendMail({
	from: "[email protected]",
	to: "[email protected]",
	subject: "Weekly Update",
	text: `# Hello!

This is a **markdown** email with:

- Bullet points
- [Links](https://example.com)
- And more!`,
	headers: {
		"X-Sidemail-Markdown": "true",
	},
});