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

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

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.

5 days agoby fenilsonani

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?

4 days agoby atmanactive