nail

A Nostr mail bridge and web client that lets users send and receive email via Nostr.

Licensed under the MIT License.

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What's in this repo

Directory	Description
nostr-bridge/	Node.js LMTP server that translates between email and Nostr events
client/	React web UI for managing your Nostr mail identity
landing/	Marketing landing page
e2e-nostr/	End-to-end test suite (Vitest + mock relay)

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How it integrates with mailcow

nail runs as a sidecar to a mailcow-dockerized deployment. It does not modify mailcow's source — it only connects via standard protocols:

• Inbound: Postfix routes matching domains to the bridge via LMTP (lmtp:inet:nostr-bridge:2400)
• Outbound: The bridge injects replies back into Postfix via SMTP on port 25

Adding nail to your mailcow docker-compose

In your mailcow docker-compose.yml, add:

nostr-bridge:
  build: ${NOSTR_BRIDGE_PATH:-./nostr-bridge}
  container_name: nostr-bridge-mailcow
  restart: always
  env_file: .env
  environment:
    - BRIDGE_DOMAIN=${NOSTR_BRIDGE_DOMAIN:-nostr-forward.local}
    - POSTFIX_HOST=postfix
    - POSTFIX_PORT=25
  networks:
    mailcow-network:
      aliases:
        - nostr-bridge

Set NOSTR_BRIDGE_PATH in your mailcow .env to the absolute path of nail/nostr-bridge, for example:

NOSTR_BRIDGE_PATH=/opt/nail/nostr-bridge
NOSTR_BRIDGE_NSEC=nsec1...
NOSTR_BRIDGE_DOMAIN=mail.yourdomain.com

Postfix transport routing

Add the following to your Postfix custom_transport.pcre (inside mailcow's data/conf/postfix/):

/@yourdomain\.com$/    lmtp:inet:nostr-bridge:2400

Then reload Postfix inside its container.

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Development

Run the bridge + a mock Nostr relay locally (no mailcow needed):

cp .env.example .env   # fill in NOSTR_BRIDGE_NSEC
docker compose up -d --build

Run the E2E test suite:

cd e2e-nostr
pnpm install
RELAY_URL=ws://127.0.0.1:4600 pnpm test