jmap-mcp

Local MCP server that exposes a Stalwart mail server's JMAP surface to an AI assistant: mail, calendar, contacts, files, sharing, Sieve.

No data leaves your machine except the exchange with your own server.

Status: early. The scaffolding, the JMAP client and the policy guard are in place. No domain tool is implemented yet, so the server currently registers zero tools.

Why

Prior art stops at mail and executes writes without asking. This server differs on two points:

• Six JMAP domains, not one.

• A write policy that gates every irreversible operation behind an explicit confirmation.

Related MCP server: fastmail-mcp

Write policy

Every tool call is classified from its arguments, not from its method name — one argument is enough to turn a write into a deletion. Each class has a configurable level: allow, confirm, or deny.

confirm relies on MRTR, the required-input pattern of MCP revision 2026-07-28. When the client does not expose it, the tool refuses — it never executes silently. Claude Desktop does not support elicitation today, so send and destroy operations fail there by design.

Configuration

Set both variables, or put the same keys in ~/.config/jmap-mcp/config.json. The environment wins.

export JMAP_SESSION_URL="https://mail.example.com/.well-known/jmap"
export JMAP_BEARER_TOKEN="…"   # never passed as a CLI argument

Optional: JMAP_ACCOUNT_ID pins one account when the session exposes several.

Register with a client

claude mcp add jmap -- npx -y jmap-mcp

Development

Requires Node 24 (nvm use) and pnpm.

pnpm install
pnpm typecheck   # tsc, native Go compiler
pnpm test        # vitest
pnpm lint        # biome
pnpm build       # emits dist/

Architecture, decisions and the full file tree live in aidd_docs/INSTALL.md. Contribution workflow in CONTRIBUTING.md.

License

MIT