A sovereign Proton Mail outpost. Multi-user, headless, self-hosted.
Reduit (French: redoubt) is a self-hosted Proton Mail relay. It serves several Proton accounts as standard SMTP and IMAPS endpoints over the network, so any mail client — phone, laptop, mutt, whatever — can use a Proton account without running Proton Bridge on every device.
The name comes from the Swiss WWII Reduit National — the strategy of withdrawal into self-sufficient Alpine fortresses to preserve sovereignty under siege. Reduit-the-software is the same idea applied to mail: your family or team can keep using Proton without surrendering daily operation to a desktop GUI on each user's laptop.
🚧 Pre-alpha. Architecture and specs are being written. No functional release yet.
- Multi-user. Designed from the start for households / teams where several people each have a Proton account.
- Headless. Daemon. No GUI. Configured via env + YAML, deployed via Docker.
- Standards-out. Speaks SMTP submission and IMAPS over TLS to your
email clients. Uses Proton Mail Bridge's official Go client
(
go-proton-api) upstream. - OIDC. Initial setup and ongoing per-user account management is gated by OIDC SSO (Pocket ID by default; any OIDC provider should work).
- MCP-enabled. Includes an integrated Model Context Protocol server exposing Proton-specific operations (labels, system folders, search) that standard IMAP/SMTP clients can't model cleanly.
- TLS via disk. Reads cert + key from disk, hot-reloads on file change. Bring your own certbot or Caddy; Reduit doesn't do ACME.
- Not Proton Bridge. Bridge is single-user, GUI, localhost-only. Reduit is multi-user, headless, network-exposed.
- Not hydroxide. Hydroxide is single-user and based on a 2017-era reverse-engineered Proton client; Reduit is multi-user and built on Proton AG's officially maintained Go client.
- Not a Proton Drive / Calendar replacement. Mail only (for now).
- Not free of operational overhead. It's still your job to run certbot / Caddy in front, point DNS, configure email clients, keep the host alive, back up the SQLite store.
See docs/adrs/ for architectural decisions and
docs/openspec/ for specifications.
MIT — copyright © 2026 Joe Stump.