Docker Mailbox MCP Server

mailbox

Read, organize, draft and send mail across multiple IMAP/SMTP accounts through one HTTP API and an MCP endpoint at /mcp, on the same port. Each bearer token controls which operations and mailboxes a client can access.

For agent access, configure tokens with explicit permissions:

• Scoped tokens. A token that holds read, draft and organize cannot send or delete, and does not even see those tools.
• Deletion defaults to Trash. Deleting moves a message to Trash. Permanent erasure needs the delete scope and only works from the Trash folder. The service never issues a folder-wide EXPUNGE.
• Drafts in two steps. An agent can prepare a reply; a human (or a token with send) sends it.
• Send guard. Hourly rate limit, dry-run mode, and a sender address that must be one of the identities you configured.
• Message analysis. Inspect SPF/DKIM/DMARC verdicts, header mismatches, hidden text and deceptive links. Verdicts are trusted only when the receiving server matches your configuration. Request sanitized HTML when needed.
• Audit log. Every write, and every refused write, is recorded (never message bodies).

Mail bodies and drafts stay on IMAP. A shared SQLite database stores audit records, send counters, checkpoints, draft send claims and webhook delivery metadata. API requests close their mail-server connections after use; the watcher keeps an IMAP connection open for notifications.

The service uses Python's imaplib and smtplib, FastAPI, the official MCP Python SDK and nh3 for HTML sanitizing. Dependency updates enforce a seven-day release-age cutoff through uv's exclude-newer setting.

Contents

• Quick start
• Configuration
• HTTP API, MCP, safety and webhooks
• Agent integrations
• Architecture and development
• Operations, backups and migration

Quick start

1. Copy config.example.yaml to config.yaml and .env.example to .env. Configure your accounts and replace every placeholder in .env with its password or a fresh token from openssl rand -hex 32. Restrict both files with chmod 600.
2. Start the container. The named volume preserves operational state across restarts:

docker run --rm \
  -p 127.0.0.1:8000:8000 \
  --env-file .env \
  -v "$PWD/config.yaml:/etc/mailboxd/config.yaml:ro" \
  -v mailboxd-state:/var/lib/mailboxd \
  psyb0t/mailbox:latest

1. Check health and list mail:

TOKEN="paste-the-token-here"

curl -s http://localhost:8000/health | jq                                               # health is always open
curl -s -H "Authorization: Bearer $TOKEN" http://localhost:8000/mailboxes | jq
curl -s -H "Authorization: Bearer $TOKEN" 'http://localhost:8000/inbox?limit=5' | jq

Docker Compose

The checked-in docker-compose.yml publishes on 127.0.0.1:${PORT:-8000}, mounts ./config.yaml (or $MAILBOXD_CONFIG) read-only and creates the mailboxd-state volume:

services:
  mailboxd:
    image: psyb0t/mailbox:latest
    ports: ["127.0.0.1:8000:8000"]
    volumes:
      # Keep config.yaml out of Git and restrict access to its credentials.
      - ./config.yaml:/etc/mailboxd/config.yaml:ro
      - mailboxd-state:/var/lib/mailboxd
volumes:
  mailboxd-state:

The optional webhook watcher is a second service in the same file, off by default: docker compose --profile watch up -d.

Capabilities

Mount /var/lib/mailboxd for persistent operational state. HTTP workers and the optional watcher share one SQLite database on a local filesystem. Read the migration notes before replacing a stateless deployment.

Development

make lint           # flake8 and mypy
make test-coverage  # full suite, production container and coverage floor
make audit          # frozen runtime and dev dependency advisories
make build          # production image
make help           # all available targets

All project tools run inside the development image. Tests use socket-level IMAP/SMTP fixtures, a local HTTP receiver, real SQLite files and a production-container smoke test. See development for details.

License

WTFPL. See LICENSE and third-party components.