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

7 points by fenilsonani 9mo ago

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 9mo ago
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 9mo ago
  Why would I pick this over established players : Maddy, Mox, Stalwart ?
  - fenilsonani 9mo ago
    Honestly if you need something battle-tested right now, those are solid choices. I built this because I had specific pain points - didn't want to set up Postgres or MySQL just for email metadata, wanted calendar and contacts baked in for a complete Google Workspace replacement, and wanted dead simple config that still does DKIM/SPF/DMARC properly. Future roadmap includes SendGrid-style stuff - API for transactional emails, webhooks. But the core idea stays: good architecture, solve real pain points, keep it simple and fast.
atmanactive 9mo ago
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 9mo ago
  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.

7 points by fenilsonani 9mo ago

fenilsonani 9mo ago

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 9mo ago
Why would I pick this over established players : Maddy, Mox, Stalwart ?
- fenilsonani 9mo ago
  Honestly if you need something battle-tested right now, those are solid choices. I built this because I had specific pain points - didn't want to set up Postgres or MySQL just for email metadata, wanted calendar and contacts baked in for a complete Google Workspace replacement, and wanted dead simple config that still does DKIM/SPF/DMARC properly. Future roadmap includes SendGrid-style stuff - API for transactional emails, webhooks. But the core idea stays: good architecture, solve real pain points, keep it simple and fast.

atmanactive 9mo ago

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 9mo ago
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.