--- slug: "mailgun" source_type: "readme" source_url: "https://cdn.jsdelivr.net/gh/mailgun/mailgun-mcp-server@main/README.md" repo: "https://github.com/mailgun/mailgun-mcp-server" source_file: "README.md" branch: "main" --- # Mailgun MCP Server [![npm version](https://img.shields.io/npm/v/@mailgun/mcp-server.svg)](https://www.npmjs.com/package/@mailgun/mcp-server) [![MCP](https://img.shields.io/badge/MCP-Server-blue.svg)](https://github.com/modelcontextprotocol) [![License](https://img.shields.io/badge/license-Apache%202.0-green.svg)](LICENSE) ## Overview A [Model Context Protocol](https://modelcontextprotocol.io) (MCP) server for [Mailgun](https://mailgun.com) that gives AI agents a practical, workflow-oriented interface to send email, diagnose deliverability, and manage account operations. > [!NOTE] > This MCP server runs locally on your machine and communicates over stdio. Mailgun does not currently offer a hosted version of this server. ### Capabilities - **Messaging** — Send emails, retrieve stored messages, resend messages - **Domains** — View domain details, verify DNS configuration, manage tracking settings (click, open, unsubscribe) - **Webhooks** — List, create, and update event webhooks - **Routes** — View and update inbound email routing rules - **Mailing Lists** — Create, view, and update mailing lists and their members - **Templates** — Create, view, and update email templates with versioning - **Analytics** — Query sending metrics, usage metrics, and logs - **Stats** — View aggregate statistics by domain, tag, provider, device, and country - **Suppressions** — View bounces, unsubscribes, complaints, and allowlist entries - **IPs & IP Pools** — View IP assignments and dedicated IP pool configuration - **Bounce Classification** — Analyze bounce types and delivery issues - **Validation** — Validate email address deliverability and syntax before sending (`validate`) - **Optimize (Inbox Placement)** — Retrieve inbox placement / seed test results to gauge deliverability (`optimize`) - **Inspect (Email Preview)** — Retrieve email rendering and preview test results across clients (`inspect`) - **Account Limits** — View custom monthly sending limits The parenthetical labels above (`validate`, `optimize`, `inspect`) are the product tags used by [tag filtering](#tag-filtering). Every other capability is registered under the `send` tag. > [!NOTE] > Tools are limited to read and update operations — no delete operations are exposed, which keeps the blast radius of an unintended action small. See [Security Considerations](#security-considerations). ### How it works The server is OpenAPI driven. At startup it parses a bundled Mailgun OpenAPI spec and registers a curated allowlist of endpoints as MCP tools, generating each tool's input schema (via Zod) from the spec. Every tool is annotated with a Mailgun product tag (`send`, `validate`, `optimize`, or `inspect`). All matching tools are registered up front — there is no lazy or on demand loading. [Tag filtering](#tag-filtering) is applied at startup to scope *which* tools get registered, so a given workflow can expose only the products it needs. ## Prerequisites - Node.js (v20.12 or higher) - Mailgun account and API key ## Installation The server is published to npm as [`@mailgun/mcp-server`](https://www.npmjs.com/package/@mailgun/mcp-server) and runs over stdio. Most clients can launch it on demand with `npx`, so there's nothing to install globally. In each snippet below, replace `YOUR-mailgun-api-key` with a key from your [Mailgun API security settings](https://app.mailgun.com/settings/api_security). > [!TIP] > If your account is hosted in Mailgun's EU region, add `"MAILGUN_API_REGION": "eu"` to the `env` block (or `-e MAILGUN_API_REGION=eu` on the CLI). It defaults to `us`. ### Claude Code ```bash claude mcp add mailgun -e MAILGUN_API_KEY=YOUR-mailgun-api-key -- npx -y @mailgun/mcp-server ``` Then run `/mcp` in Claude Code to confirm the **mailgun** server is connected. ### Claude Desktop Open **Settings → Developer → Edit Config**, or edit the file directly: - macOS: `~/Library/Application Support/Claude/claude_desktop_config.json` - Windows: `%APPDATA%/Claude/claude_desktop_config.json` ```json { "mcpServers": { "mailgun": { "command": "npx", "args": ["-y", "@mailgun/mcp-server"], "env": { "MAILGUN_API_KEY": "YOUR-mailgun-api-key", "MAILGUN_API_REGION": "us" } } } } ``` ### Cursor Open the command palette and choose **Cursor Settings → MCP → Add new global MCP server**, then add: ```json { "mcpServers": { "mailgun": { "command": "npx", "args": ["-y", "@mailgun/mcp-server"], "env": { "MAILGUN_API_KEY": "YOUR-mailgun-api-key" } } } } ``` ### Codex ```bash codex mcp add mailgun \ --env MAILGUN_API_KEY=YOUR-mailgun-api-key \ -- npx -y @mailgun/mcp-server ``` ### VS Code (GitHub Copilot) Add the following to your `settings.json`: ```json { "mcp": { "servers": { "mailgun": { "command": "npx", "args": ["-y", "@mailgun/mcp-server"], "env": { "MAILGUN_API_KEY": "YOUR-mailgun-api-key" } } } } } ``` ### Windsurf ```json { "mcpServers": { "mailgun": { "command": "npx", "args": ["-y", "@mailgun/mcp-server"], "env": { "MAILGUN_API_KEY": "YOUR-mailgun-api-key" } } } } ``` ### Gemini CLI Add to `~/.gemini/settings.json`: ```json { "mcpServers": { "mailgun": { "command": "npx", "args": ["-y", "@mailgun/mcp-server"], "env": { "MAILGUN_API_KEY": "YOUR-mailgun-api-key" } } } } ``` ## Configuration ### Environment variables | Variable | Required | Default | Description | | ---------------------- | -------- | -------------------- | ------------------------------------------------------------------------------------------- | | `MAILGUN_API_KEY` | Yes | — | Your Mailgun API key | | `MAILGUN_API_REGION` | No | `us` | API region: `us` or `eu` | | `MAILGUN_API_HOSTNAME` | No | (derived from region) | Override the API hostname (e.g. `api.eu.mailgun.net`). Takes precedence over the region. | | `MAILGUN_MCP_TAGS` | No | (all) | Comma-separated product tags to enable. Equivalent to `--tags`. The CLI flag takes precedence. | ### CLI options Pass flags after the package name in your client's `args` (e.g. `["-y", "@mailgun/mcp-server", "--tags", "validate,inspect"]`). | Flag | Description | | ----------------- | -------------------------------------------------------------------------------------- | | `--tags ` | Comma-separated product tags to enable (default: all). Valid: `send`, `validate`, `optimize`, `inspect`. | | `--list-tags` | Print the valid tag values and exit. | | `--help`, `-h` | Show usage and exit. | ### Tag filtering You can scope which tools the server registers to one or more Mailgun product tags. This is useful for narrowing the toolset shown to the model — for example, only exposing validation tools to a workflow that doesn't need send capabilities. Valid tags: `send`, `validate`, `optimize`, `inspect`. When unspecified, every tool is registered (today's default). Filtering uses **OR semantics**: a tool is registered if any of its tags appears in the active set. **Via CLI flag** — pass `--tags` in your MCP client config's `args`: ```json { "mcpServers": { "mailgun": { "command": "npx", "args": ["-y", "@mailgun/mcp-server", "--tags", "validate,inspect"], "env": { "MAILGUN_API_KEY": "YOUR-mailgun-api-key" } } } } ``` **Via environment variable** — set `MAILGUN_MCP_TAGS` (CLI flag wins if both are present): ```json "env": { "MAILGUN_API_KEY": "YOUR-mailgun-api-key", "MAILGUN_MCP_TAGS": "validate,inspect" } ``` > [!TIP] > Run the binary with `--list-tags` to print supported tag values, or `--help` for full usage. Unknown tags are rejected at startup with a clear error message. ## Sample Prompts #### Send an Email ``` Can you send an email to EMAIL_HERE with a funny email body that makes it sound like it's from the IT Desk from Office Space? Please use the sending domain DOMAIN_HERE, and make the email from "postmaster@DOMAIN_HERE"! ``` > [!NOTE] > Some MCP clients require a paid plan to invoke tools that send data. If sending fails silently, check your client's plan. #### Fetch and Visualize Sending Statistics ``` Would you be able to make a chart with email delivery statistics for the past week? ``` #### Manage Templates ``` Create a welcome email template for new signups on my domain DOMAIN_HERE. Include a personalized greeting and a call-to-action button. ``` #### Investigate Deliverability ``` Can you check the bounce classification stats for my account and tell me what the most common bounce reasons are? ``` #### Troubleshoot DNS ``` Check the DNS verification status for my domain DOMAIN_HERE and tell me if anything needs fixing. ``` #### Review Suppressions ``` Are there any unsubscribes or complaints for DOMAIN_HERE? Summarize the top offenders. ``` #### Manage Routing Rules ``` List all my inbound routes and explain what each one does. ``` #### Create a Mailing List ``` Create a mailing list called announcements@DOMAIN_HERE and add these members: alice@example.com, bob@example.com. ``` #### Compare Domains ``` Compare my sending volume and delivery rates across all my domains for the past month. ``` #### Engagement by Region ``` Break down my email engagement by country and device for DOMAIN_HERE. ``` #### Review Tracking Settings ``` List all my domains and show which ones have tracking enabled for clicks and opens. ``` #### Validate an Email Address ``` Validate the email address EMAIL_HERE and tell me whether it's safe to send to. ``` #### Check Inbox Placement (Optimize) ``` Pull the inbox placement results for seed test RESULT_ID_HERE and summarize where my message landed (inbox, spam, or missing) by provider. ``` #### Preview an Email (Inspect) ``` Get the email preview results for test TEST_ID_HERE and tell me if the email renders correctly across clients. ``` ## Development ### Run from source The server is written in TypeScript. Clone, install, build, and test: ```bash git clone https://github.com/mailgun/mailgun-mcp-server.git cd mailgun-mcp-server npm install npm run build npm test ``` `npm run build` compiles `src/` to `dist/` and copies the bundled OpenAPI spec. Point your MCP client at the built entry instead of `npx` (use an absolute path): ```json { "mcpServers": { "mailgun": { "command": "node", "args": ["/absolute/path/to/mailgun-mcp-server/dist/mailgun-mcp.js"], "env": { "MAILGUN_API_KEY": "YOUR-mailgun-api-key" } } } } ``` ### Live testing while you edit MCP servers are long-lived stdio processes that don't hot-reload, so the loop is: rebuild on save, then reconnect the client to pick up changes. 1. Run `npm run build` once so `dist/openapi.yaml` is in place. 2. Keep the TypeScript compiler running to rebuild `dist/` on every save: ```bash npx tsc --watch ``` 3. Point a separate MCP client (or MCP Inspector, below) at `dist/mailgun-mcp.js`. After a change, restart the MCP client session to load the new build. ### Testing with MCP Inspector The [MCP Inspector](https://modelcontextprotocol.io/docs/tools/inspector) lets you exercise tools without a full client. Build first, then launch it against the built server: ```bash npm run build MAILGUN_API_KEY=YOUR-mailgun-api-key npx @modelcontextprotocol/inspector node dist/mailgun-mcp.js ``` Open the Inspector UI, click **Connect**, then use **List Tools** to verify the server is working. To test a filtered toolset, append flags after the server path: ```bash MAILGUN_API_KEY=YOUR-mailgun-api-key npx @modelcontextprotocol/inspector node dist/mailgun-mcp.js --tags validate,inspect ``` ### Pre-commit hooks `npm install` installs a git pre-commit hook (via husky) that runs `oxlint --fix` and `oxfmt` on staged TypeScript/JavaScript files and runs `npm run check:versions`. Fixable issues are auto-fixed and re-staged; commits that introduce unfixable lint errors or version-sync mismatches are rejected. If you already had a local clone before this change, run `npm install` once to install the hook. ### Note on adding [endpoints](https://github.com/mailgun/mailgun-mcp-server/blob/main/src/endpoints.ts) When adding a new endpoint if you use a plain string for it's definition it will default to being tagged with the `send` product type in the `_meta` field. If you would like to tag it as a different product use the object version of the `EndpointEntry` type. ## Security Considerations ### API key isolation Your Mailgun API key is passed as an environment variable and is never exposed to the AI model itself — it is only used by the MCP server process to authenticate requests. The server does not log API keys, request parameters, or response data. ### Local execution The server runs locally on your machine. All communication with the Mailgun API is over HTTPS with TLS certificate validation enforced. No data is sent to third-party services beyond the Mailgun API. ### API key permissions Use a dedicated Mailgun API key with permissions scoped to only the operations you need. The server exposes read and update operations but does not expose any delete operations, which limits the blast radius of unintended actions. ### Rate limiting The server does not implement client-side rate limiting. Each tool call from the AI translates directly into a Mailgun API request. The server relies on Mailgun's server-side rate limits to prevent abuse — requests that exceed those limits will return an error to the AI assistant. ### Prompt injection As with any MCP server, a crafted or adversarial prompt could trick the AI assistant into calling operations you did not intend — for example, modifying tracking settings or reading mailing list members. Review your AI assistant's tool-call confirmations before approving actions, especially in untrusted prompt contexts. ### Webhook URLs Webhook create and update operations accept arbitrary URLs provided through the AI assistant. The MCP server passes these URLs to the Mailgun API without additional validation. Mailgun is responsible for validating webhook destinations. Ensure your AI assistant does not set webhook URLs to unintended internal or sensitive addresses. ### Input validation All tool parameters are validated against the Mailgun OpenAPI specification using Zod schemas. However, validation depends on the accuracy of the OpenAPI spec, and some edge-case parameters may fall back to permissive validation. The Mailgun API performs its own server-side validation as an additional layer of protection. ## Debugging The MCP server communicates over stdio. Refer to the [MCP Debugging Guide](https://modelcontextprotocol.io/docs/tools/debugging) for troubleshooting. ## License Apache 2.0 — see [LICENSE](https://github.com/mailgun/mailgun-mcp-server/tree/HEAD/LICENSE) for details. ## Contributing We welcome contributions! Please feel free to submit a [Pull Request](https://github.com/mailgun/mailgun-mcp-server/pulls) or open an [Issue](https://github.com/mailgun/mailgun-mcp-server/issues).