EngageLab Agent Email MCP Server

English | 简体中文

Send, receive, and reply to email from AI agents — through the Model Context Protocol.

Each agent gets its own mailbox: a real address that sends and receives, with conversations grouped into threads so your agent has context. Works with Claude Desktop, Claude Code, Cursor, Cowork, and any MCP-compatible client.

{
  "mcpServers": {
    "engagelab-email": {
      "command": "npx",
      "args": ["-y", "@engagelabemail/mcp"],
      "env": { "ENGAGELAB_EMAIL_SECRET_KEY": "sk_sg_your_key" }
    }
  }
}

Why

Most email APIs are send-only. Agents that need to have a conversation over email — support, scheduling, approvals — need an inbox.

• Send & receive — the agent owns a dedicated mailbox, not a bolted-on parse webhook
• Thread-aware — replies group into conversations, so the agent sees full history
• Sandbox mode — test agent flows without emailing real humans
• One env var — no OAuth dance for local use; region inferred from the key

Tools

	Tool	What it does
Discover	list_mailboxes	List mailboxes; call this first to get IDs
Send	send_email	New email (text/html, cc/bcc, attachments, sandbox)
	reply_email	Reply to a message — recipients & thread inferred
Receive	list_inbound_messages	Inbound mail, filter by mailbox/keyword
	get_message	Full message details by UID
	check_new_messages	One-shot poll for new mail
Threads	list_threads / get_thread / list_thread_messages	Browse conversations

Quickstart

1. Get a Secret Key. Create an EngageLab account and generate a key from the console (format sk_sg_xxx — the prefix selects the region). Or use the CLI: engagelab-email-cli login creates one via browser.

2. Create a mailbox. In the console, create a mailbox for your agent (shared subdomain is instant; custom domains need DNS verification). Programmatic mailbox creation is on the roadmap — see Troubleshooting if list_mailboxes returns empty.

3. Register the server.

Claude Desktop — add the JSON block above to claude_desktop_config.json.

Claude Code:

claude mcp add engagelab-email \
  -e ENGAGELAB_EMAIL_SECRET_KEY=sk_sg_your_key \
  -- npx -y @engagelabemail/mcp

Then ask your agent:

List my mailboxes, then send an email from the first one to bob@example.com saying the invoice is approved.

A typical agent loop for a support bot:

check_new_messages()            → [messageUids]
get_message(uid)                → body, attachments
list_thread_messages(threadId)  → full conversation context
reply_email(uid, { text: ... }) → response lands in the same thread

Configuration

Environment variable	Required	Description
ENGAGELAB_EMAIL_SECRET_KEY	Yes	Secret Key starting with sk_
ENGAGELAB_EMAIL_BASE_URL	No	Override the API base URL. Inferred from the key region: sg → Singapore, tr → Türkiye

Limits: up to 10 attachments / 10MB total per message (base64-encoded in the tool schema).

Troubleshooting

• list_mailboxes returns an empty list — your account has no mailbox yet. Create one in the EngageLab console (see Quickstart step 2). Agents cannot self-provision mailboxes yet.
• 401 / code 100101 — the Secret Key is wrong or revoked. Check ENGAGELAB_EMAIL_SECRET_KEY and that the key's region prefix (sk_sg_ / sk_tr_) matches the endpoint you use.
• Could not determine API base URL — the key's region prefix isn't recognized. Set ENGAGELAB_EMAIL_BASE_URL explicitly.
• Reply shows up as a new conversation — use reply_email (not send_email) so In-Reply-To headers and threading stay intact.

Roadmap

• [ ] Hosted MCP (OAuth) for zero-config remote use
• [ ] Programmatic mailbox creation via Secret Key
• [ ] Webhook push (no polling) for check_new_messages
• [ ] URL-based attachment references (no base64 in context)

Run from source

git clone https://github.com/Metaverse-Cloud/engagelab-email-mcp
cd engagelab-email-mcp
npm install && npm run build
ENGAGELAB_EMAIL_SECRET_KEY=sk_sg_xxx node dist/index.cjs

Related

• EngageLab Agent Email CLI — same mailboxes from the terminal, --json output for agents
• EngageLab Node SDK / Python SDK — send email from code

License

MIT