Show HN: Self-hosted email server for 2026 – single binary, CalDAV

[fenilsonani]

Built this after getting frustrated with the paying to a google for email. Now running it for 1 months in production.

What it does: - Full SMTP server (inbound/outbound, DKIM signing, SPF/DMARC checking) - IMAP with IDLE support - CalDAV/CardDAV (replace Google Calendar/Contacts) - Web admin panel with Prometheus metrics - Greylisting for spam prevention - Auto-discovery (mail clients configure themselves) - Audit logging for compliance

What it doesn't do: - Webmail (use Roundcube, etc.) - ML-based spam filtering (greylisting + basic heuristics only) - Clustering/HA

[fenilsonani]

I built this after Google Workspace pricing jumped again and I wanted full control over my email stack.

This is a self-hosted email server written in Go, shipped as a single binary. It supports IMAP (with IDLE), SMTP, DKIM, SPF/DMARC, and CalDAV, with modern defaults and minimal configuration.

The goal is something you can run on a small VPS for personal or small-team use without vendor lock-in.

I’d really appreciate feedback on the architecture, security model, and what you’d want to see next.

[slooonz]

Why would I pick this over established players : Maddy, Mox, Stalwart ?

[atmanactive]

Very interesting, thanks for sharing. Looking at the /etc/mailserver/config.yaml example from README.md, I couldn't help but notice that the Bind-To Listening IP is missing. What happens if I have a multi homed machine with several IPs? Does the server gloom on all IPs?

[fenilsonani]

Yeah you caught that - right now it just binds to all interfaces by default. Definitely need to add a bind_address option in the config. That's going on my list.

If you're on a multi-homed setup right now, firewall rules would be the workaround, but I hear you - it should be in the config properly.

Thanks for the feedback, this is exactly what I was hoping to get from posting here.