Mimecast MCP Server

An MCP server for the Mimecast API 2.0, the email security gateway MSPs run in front of their clients' mailboxes. It lets an AI agent track where an email went, review and release held messages, read Targeted Threat Protection logs (URL clicks, attachment sandboxing, impersonation), list threat remediation incidents, read the audit log of administrative changes and check the inbound / outbound mail queues.

• Transport: MCP Streamable HTTP at POST /mcp, health probe at GET /health

• Stateless and multi-tenant: credentials arrive on every request as HTTP headers and are never stored; every tool is listed from the first tools/list

• Python 3.12, uv, FastMCP, httpx

• License: Apache-2.0, Copyright 2026 MSPbots.ai

Authentication headers

Where to get them: in the Mimecast Administration Console go to Administration > Services > API and Platform Integrations > Available Integrations, and choose Generate Keys on the Mimecast API 2.0 tile. Give the application a role with only the permissions the tools below need.

How they are used: the server exchanges the client id and secret for an access token (POST https://api.services.mimecast.com/oauth/token, client credentials grant, 30 minute lifetime, cached in memory per credential set and renewed on expiry) and sends it as Authorization: Bearer. Region codes all use the global gateway, which serves every account and fails over between regions; us-api, uk-api and de-api pin traffic to that regional gateway (data residency, no failover).

A request to /mcp without the client id or secret gets HTTP 401; an unknown region gets HTTP 400.

Related MCP server: Avanan (Legacy) MCP Server

Tools

All tools return a JSON string. Lists take page_size (max 100) and page_token, and return {count, has_more, next_page_token}. Dates are ISO 8601 with a zone (2026-03-01T00:00:00Z or +0000).

Bold parameters are required. mimecast_release_message returns {"done": false, ...} until it is called again with confirm: true after the user approved releasing that message.

Errors come back as a JSON envelope instead of an exception:

{"error": {"code": "unauthorized", "message": "Mimecast rejected the client id / client secret (...)", "retryable": false}}

code is one of not_configured, unauthorized, not_found, invalid_argument, rate_limited, upstream_error. Mimecast reports per-item failures inside an HTTP 200 response (fail); those become the same envelope. Reads are retried with backoff on 429 (honouring X-RateLimit-Reset), 5xx and network errors; a release only on 429, so it never runs twice. An expired or revoked token is renewed once automatically.

Run locally

uv sync
uv run python -m mimecast_mcp          # listens on 0.0.0.0:8080

or with Docker:

docker build --platform linux/amd64 -t mimecast-mcp:dev .
docker run --rm -p 8080:8080 mimecast-mcp:dev

Configuration (environment variables, all optional): MCP_HTTP_HOST (default 0.0.0.0), MCP_HTTP_PORT (default 8080), LOG_LEVEL (default INFO). Credentials are never read from the environment.

Testing example

# list tools
curl -s http://localhost:8080/mcp \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -H "X-Mimecast-Client-ID: your-client-id" \
  -H "X-Mimecast-Client-Secret: your-client-secret" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list","params":{}}'

# where did mail from a sender go today
curl -s http://localhost:8080/mcp \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -H "X-Mimecast-Client-ID: your-client-id" \
  -H "X-Mimecast-Client-Secret: your-client-secret" \
  -d '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"mimecast_find_message","arguments":{"sender_address":"billing@example.org"}}}'

Unit tests (no network access needed):

uv run pytest

Delivery notes

• Tool names (10 earlier + 1 new). The ten earlier names and their required parameters are unchanged. New: mimecast_list_held_messages, because releasing needs the held-message id, which only that list returns (message tracking ids are different).

• API source. The official Mimecast API 2.0 OpenAPI documents published on developer.services.mimecast.com (Email Security Cloud Gateway, Security Events, Audit Events, Threat Management) and its API Overview (token, pagination, regional gateways, rate limits).

• Routes fixed. Earlier versions called endpoints that do not exist in the API: /api/gateway/release-message (now /api/gateway/hold-release), /api/gateway/get-queue-stats (now /api/email/get-email-queues, which needs a time window: default the last hour) and /api/ttp/remediation/get-incidents (now /api/ttp/remediation/find-incidents, default the last 30 days).

• Results fixed. Message tracking and remediation results are nested in the response (trackedEmails, incidents); earlier versions returned the wrapper, so the count was always 1.

• Message tracking filters now use the API's fields: sender / recipient go to the advanced tracking options, value searches the subject (or is used as the internet message id when it looks like <id@host>), and status uses the tracking states. The earlier status names map to them: delivered = delivery + archived, blocked = rejected, failed = bounced, queued = delivery.

• mimecast_hold_message is not available: the API has no call that puts a message on hold (messages are held by policy). The tool stays for compatibility and returns invalid_argument pointing to the held-message list and to threat remediation in the console.

• Removed: the status filter of mimecast_get_threat_incidents (the API has no such field, so it never filtered); it is replaced by type (notify_only, automatic, manual, restore) and a search on code / file hash / reason. The incident type filter is sent as {"fieldName": "type", "value": ...}, the API's usual filter form; the reference's wording for this endpoint is ambiguous and it has not been checked against a live account.

• Release needs confirmation (confirm: true): releasing delivers mail that a policy held, possibly malicious.

• Not included: the message "card" UI resource of older versions (an MCP Apps HTML view); the tools return the same data as JSON. Credentials from environment variables are not supported: they would be shared by every caller.

License

Apache License 2.0 - see LICENSE and NOTICE.