OpenMail

What OpenMail MCP server does

The OpenMail MCP server gives AI agents access to hosted email workflows through MCP. It supports creating inboxes, reading mail identified as needing a reply, replying within an existing thread, sending email, and managing domains. The service is presented as Gmail for agents, but the README identifies OpenMail as the connected hosted system.

The server is useful for agents that need to monitor an inbox, draft or send responses, and preserve conversation context. It can also support workflows that provision inboxes or work with domains. The available operations are exposed remotely rather than through a local catalog.

How it works

OpenMail provides a Streamable HTTP MCP endpoint at https://mcp.openmail.sh/mcp. A compatible client connects to that URL and authenticates either through OAuth or an API key. Claude and Cursor can use OAuth sign-in. Cursor and headless agents can instead send an Authorization: Bearer header with an API key.

Access can be narrowed with a read-only endpoint at /mcp/readonly or to one inbox with /mcp/inbox/{id}. The README recommends using an inbox-scoped key where possible. OAuth sessions do not return tokens from setup_agent_email or mint_inbox_key; those flows direct the user to the console, where a new key is displayed. With API-key authentication, the token is returned in the tool result and should be moved into the agent's environment.

Setup and configuration

For Claude, paste the hosted MCP URL into the client. Cursor can use the provided installation link or the same URL without headers. Claude Code supports the claude mcp add --transport http command and also provides a plugin that includes an email-handling skill. VS Code and other registry clients can find the server under sh.openmail/openmail in the MCP Registry.

Clients that only support stdio can connect through npx -y mcp-remote https://mcp.openmail.sh/mcp. For API-key access, configure the URL and an Authorization header containing the bearer token.

The repository also documents local development commands: pnpm install, pnpm test, and pnpm dev. Server configuration includes the API origin, OAuth resource URL, JWT secret, consent-page origin, listen port, and optional PostHog analytics settings. MCP_JWT_SECRET is required in production; outside production, the README says it falls back to NEXTAUTH_SECRET.

Tools and capabilities

• Create agent inboxes.
• Read mail that needs a reply.
• Reply in an existing email thread.
• Send email messages.
• Manage domains.
• Create or mint inbox access through the documented setup flows.

Limitations and notes

The OpenMail MCP server is hosted over Streamable HTTP and does not provide a local stdio catalog. Stdio-only clients therefore need mcp-remote. OAuth authentication is session-based, so token creation details differ from API-key access. PostHog MCP analytics are disabled unless POSTHOG_API_KEY is set; MCP_ANALYTICS_DEBUG enables logging of captured analytics events.