Self-Hosting an Email Newsletter

My friend Cory asked if there was a way to subscribe to blog updates via email. Now I can proudly say: Yes, I have a newsletter! If you’d like to receive a weekly email with blog updates, fill out the form below (you can unsubscribe at any time).

Cory uses EmailOctopus to send his newsletter. I probably should have copied him, but I’m super frugal and didn’t want to spend $10 per month. I’ve set up my newsletter using:

1. listmonk on my home server
2. Cloudflare Tunnel exposing listmonk to the web
3. Mailgun to send emails via SMTP¹

This costs me $0 per month! I think listmonk is very good, but the signup process for new subscribers is a little clunky. I might try Keila next (it looks a bit smoother than listmonk, though less mature).

Double vs Single Opt-In

I found listmonk’s double opt-in process confusing. When a user tried to subscribe, they would receive a confirmation email. However, pressing the blue “Confirm subscription” button in the email didn’t immediately confirm their subscription. Instead, it redirected them to a website where they had to submit another form. I would have preferred the button to directly confirm the subscription without this extra step. Since I couldn’t find a way to achieve that behavior with listmonk, I’ve switched to a single opt-in process.

CORS Configuration

CORS (Cross-Origin Resource Sharing) is a browser security feature that restricts web pages from making requests to a different “origin” than the one that served the page. An origin is defined by the combination of protocol, host, and port - so andrewmarder.net and newsletter.andrewmarder.net are considered different origins, even though they’re subdomains of the same domain.

If you’re using a Cloudflare Tunnel to expose listmonk and want your subscription form to work via JavaScript fetch() requests, you’ll need to configure CORS headers. Without this, browsers will block the response - both in local development and in production.

In your Cloudflare dashboard, select the domain you want to modify, then go to Rules → Overview → Create rule → Response Header Transform Rule:

• When: Hostname equals your listmonk domain (e.g., newsletter.yourdomain.com)
• Then: Set these static response headers:

Header name	Value
Access-Control-Allow-Origin	*
Access-Control-Allow-Methods	POST, GET, OPTIONS
Access-Control-Allow-Headers	Content-Type

I used * for the allowed origin so the form works in both production and local development. This approach seems acceptable for a public subscription endpoint, but I’m not thrilled with opening things up to every origin.

Footnotes

1. Initially, I sent emails via Proton Mail’s SMTP, but it wasn’t working smoothly. I’ve switched to Mailgun, which lets me send up to 100 emails a day for free. ↩

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