Simplelogin MCP

What simplelogin-mcp MCP server does

The simplelogin-mcp MCP server exposes selected SimpleLogin account operations to MCP-compatible clients. It is intended for existing SimpleLogin users who want an agent to work with aliases, contacts, reverse aliases, mailboxes, custom domains, notifications, and account settings.

Alias workflows include listing and inspecting aliases, creating random or custom aliases, updating notes, names, and pinned state, and enabling or disabling an alias. Activity inspection returns metadata about forwards, replies, blocks, and bounces; it does not expose email message bodies.

The server can also create routing addresses for reverse aliases. It does not compose or send the resulting email. Mailbox operations cover listing, creation, updates, and deletion, while custom-domain support is limited to inspecting and updating supported settings for an existing domain.

How it works

The server authenticates to SimpleLogin with an API key supplied through the environment. An MCP client launches it locally using stdio, or connects to a persistent Streamable HTTP process. HTTP deployments can run directly with Node.js or through Docker Compose.

The tool catalog includes operations such as alias_list, alias_get, alias_create_random, alias_create_custom, alias_update, alias_set_enabled, alias_activity_list, contact_list, contact_create, mailbox_list, account_get_stats, notification_list, settings_get, and settings_update.

Potentially large read results are bounded. Permanent mailbox deletion requires confirm: true and an explicit decision about transferring or deleting owned aliases. These controls make destructive operations require an additional deliberate input.

Setup and configuration

A SimpleLogin account and a dedicated API key are required. Source installation requires Git, Node.js 24.x, Corepack, and pnpm 11.5.1. The documented source flow installs dependencies, builds the project, and points the MCP client at the absolute path to dist/index.js.

For local use, configure TRANSPORT=stdio and SL_API_KEY in the MCP client's private configuration. For a persistent service, Docker Compose can pull the published container image, or a local Docker Compose file can build from source. Direct HTTP operation uses TRANSPORT=http, with the listener defaulting to 127.0.0.1:3000 and the MCP endpoint at POST /mcp.

SL_API_URL selects the hosted or self-hosted SimpleLogin web-app origin. HOST and PORT configure the direct HTTP listener. MCP_AUTH_TOKEN protects the HTTP MCP endpoint and is required for normal non-loopback startup. Keep the SimpleLogin API key and HTTP bearer token out of prompts, logs, shell history, and version control.

Tools and capabilities

The simplelogin-mcp MCP server supports these practical workflows:

• Find existing aliases before creating or changing them.
• Create random aliases or custom aliases after checking available options.
• Review bounded alias activity metadata.
• Create or reuse reverse aliases for a recipient.
• Manage mailbox records with verification handled by SimpleLogin.
• Inspect and update supported settings for existing custom domains.
• Review aggregate account statistics and bounded notifications.
• Read settings before applying supported updates.

Limitations and notes

This is an independent, open-source project rather than an official SimpleLogin or Proton AG product. It requires a SimpleLogin API key with full account control, so deployment security and credential handling are important.

The server does not read message content, compose mail, or send mail. Domain creation, deletion, DNS configuration, and MX verification remain outside the server in SimpleLogin's official interface. The server also covers only the API endpoints and settings documented by its tool catalog; consult the current catalog and API-coverage documentation before depending on a specific operation.

HTTP deployments bind to loopback by default in the documented Node.js and Compose setups. Widening network exposure requires the appropriate authentication and deployment configuration.