resend-email-mcp

# resend-email-mcp **The most complete [Resend](https://resend.com) MCP server** — full coverage of the Resend API (emails, domains, contacts, broadcasts, templates, segments, topics, webhooks, logs) **plus a unique debug/diagnostics layer** no other Resend MCP offers: deliverability analysis, DNS troubleshooting, email lifecycle inspection, bounce explanation, and account auditing. Works with **Claude Code, Cursor, Claude Desktop**, and any other MCP client. 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Get a Resend API key Create one at **https://resend.com/api-keys**. ### 2. Add to your MCP client #### Claude Code (CLI) ```bash claude mcp add resend -e RESEND_API_KEY=re_xxxxxxxx -- npx -y resend-email-mcp ``` #### Cursor / Claude Desktop / generic (`mcp.json` / `claude_desktop_config.json`) ```json { "mcpServers": { "resend": { "command": "npx", "args": ["-y", "resend-email-mcp"], "env": { "RESEND_API_KEY": "re_xxxxxxxx", "RESEND_FROM": "Acme <hello@acme.com>" } } } } ``` Config file locations: - **Claude Desktop (Windows):** `%APPDATA%\Claude\claude_desktop_config.json` - **Claude Desktop (macOS):** `~/Library/Application Support/Claude/claude_desktop_config.json` - **Cursor:** `~/.cursor/mcp.json` (or per-project `.cursor/mcp.json`) Restart the client and ask: *"Send a test email to delivered@resend.dev"* or *"Audit my Resend account."* --- ## Configuration | Env var | Required | Description | |---------|:---:|-------------| | `RESEND_API_KEY` | ✅ | Your Resend API key | | `RESEND_FROM` | – | Default sender for `send_email` when `from` is omitted (must be a verified domain) | | `RESEND_REPLY_TO` | – | Default Reply-To address | | `RESEND_READONLY` | – | `true` blocks every mutating tool (send/create/update/delete). Safe exploration of production | | `RESEND_ATTACHMENTS_DIR` | – | Directory that `send_email`'s `localPath` attachments are restricted to. **Unset = disk reads disabled** (safe default; path traversal is blocked) | | `RESEND_BASE_URL` | – | Override API base URL (default `https://api.resend.com`). Must be https (http only for localhost) | | `RESEND_MAX_RETRIES` | – | Retries on 429/5xx (default `3`) | --- ## Tools ### Emails `send_email` · `send_batch_emails` · `get_email` · `list_emails` · `update_email` · `cancel_email` · `preview_email` > `send_email` accepts attachments by base64 `content`, public `path` (URL), or **`localPath`** (a file on disk, read and base64-encoded automatically — only enabled when `RESEND_ATTACHMENTS_DIR` is set, and restricted to that directory). `preview_email` dry-runs a message — resolving the final sender, sizing attachments, and surfacing warnings — **without sending**. ### Attachments (sent & received) `list_email_attachments` · `get_email_attachment` · `list_received_emails` · `get_received_email` · `list_received_attachments` · `get_received_attachment` ### Domains `create_domain` · `get_domain` · `list_domains` · `update_domain` · `delete_domain` · `verify_domain` ### API keys `create_api_key` · `list_api_keys` · `delete_api_key` ### Broadcasts `create_broadcast` · `get_broadcast` · `list_broadcasts` · `update_broadcast` · `send_broadcast` · `delete_broadcast` ### Contacts `create_contact` · `get_contact` · `list_contacts` · `update_contact` · `delete_contact` · `get_contact_topics` · `update_contact_topics` · `list_contact_segments` · `add_contact_to_segment` · `remove_contact_from_segment` ### Contact properties `create_contact_property` · `get_contact_property` · `list_contact_properties` · `update_contact_property` · `delete_contact_property` ### Segments `create_segment` · `get_segment` · `list_segments` · `delete_segment` · `list_segment_contacts` ### Templates `create_template` · `get_template` · `list_templates` · `update_template` · `delete_template` · `publish_template` · `duplicate_template` ### Topics `create_topic` · `get_topic` · `list_topics` · `update_topic` · `delete_topic` ### Webhooks `create_webhook` · `get_webhook` · `list_webhooks` · `update_webhook` · `delete_webhook` ### Logs `list_logs` · `get_log` ### 🔍 Debug & diagnostics (the differentiator) | Tool | What it does | |------|--------------| | `diagnose_domain` | Inspects every DNS record (SPF/DKIM/DMARC) and reports what's missing + how to fix it | | `analyze_deliverability` | Aggregates recent sends into delivery/bounce/complaint rates with a health verdict | | `inspect_email` | Renders one email's full lifecycle timeline and flags problems | | `explain_bounce` | Classifies a bounce (hard/soft/block) and recommends the action | | `audit_account` | One-shot health check of domains, keys, and deliverability | | `search_logs` | Smart filtering of API logs by status/path/recipient to find failures | | `test_send` | Safely simulates delivered/bounced/complained via Resend sandbox addresses | ### Escape hatch `resend_raw` — call any Resend endpoint not yet wrapped in a dedicated tool. ## Resources Beyond tools, the server exposes two read-only **MCP resources** so a client can pull account context without spending a tool call: | URI | Content | |-----|---------| | `resend://account` | Domains + API keys snapshot | | `resend://domains` | All sending domains with verification status | Every tool is annotated with MCP hints (`readOnlyHint`, `destructiveHint`, `idempotentHint`) so clients can show which operations are safe and which need confirmation. --- ## Example prompts - *"Diagnose why acme.com isn't verified."* → `diagnose_domain` - *"How healthy is my email sending this week?"* → `analyze_deliverability` - *"What happened to email re_abc123?"* → `inspect_email` - *"Why did that email bounce and what should I do?"* → `explain_bounce` - *"Something's wrong with my Resend setup — check everything."* → `audit_account` - *"Send our launch newsletter to the 'beta' segment."* → `create_broadcast` + `send_broadcast` --- ## Testing safely Use Resend's sandbox addresses (no reputation impact): - `delivered@resend.dev` — simulates delivery - `bounced@resend.dev` — simulates a hard bounce - `complained@resend.dev` — simulates a spam complaint Or just run `test_send` and then `inspect_email` on the returned ID. Enable `RESEND_READONLY=true` to explore a production account without any risk of sending or deleting. --- ## Troubleshooting This MCP is built to debug itself — when something fails, reach for the diagnostic tools instead of guessing. | Symptom / error | Likely cause | What to run | |-----------------|--------------|-------------| | `validation_error: from domain is not verified` | Your `from`/`RESEND_FROM` domain isn't verified | `list_domains` → `diagnose_domain` (shows missing DNS records + fixes) → `verify_domain` | | Emails send but never arrive | Deliverability / reputation issue | `analyze_deliverability` then `inspect_email` on a sample ID | | `missing_api_key` / `invalid_api_key` (HTTP 401) | `RESEND_API_KEY` unset or wrong | Check the `.env`; create a key at resend.com/api-keys | | `restricted_api_key` / `not_authorized` (403) | Key scoped to sending-only or one domain | Use a `full_access` key (`list_api_keys` to inspect) | | `rate_limit_exceeded` (429) | Too many requests | The client auto-retries with backoff; reduce volume | | `daily_quota_exceeded` | Plan send limit reached | Upgrade plan or wait for reset | | A specific email bounced | Invalid/blocking recipient | `explain_bounce` (classifies hard/soft/block + action) | | "Is anything wrong with my setup?" | — | `audit_account` (one-shot health check) | | Request fails for unknown reason | — | `search_logs` with `only_errors: true` | Every error returned by this server includes the HTTP status, Resend's error name, and an actionable **Hint** line. --- ## Local development ```bash git clone https://github.com/helbertparanhos/resend-email-mcp.git cd resend-email-mcp npm install npm run build cp .env.example .env # add your RESEND_API_KEY npm run inspector # opens the MCP Inspector against the built server ``` --- ## License MIT © [Helbert Paranhos / Strat Academy](https://stratacademy.com.br) Built with the [Model Context Protocol](https://modelcontextprotocol.io). Not affiliated with Resend.