EngageLab Agent Email MCP Server

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Official EngageLab Email project.

This repository distributes a local stdio MCP server. It does not provide a hosted OAuth or HTTP MCP endpoint; run it locally with the installation command below.

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

Smithery / MCPB

For local stdio distribution, build an MCPB bundle:

npm run build:mcpb

The bundle is generated at dist/engagelab-agent-email.mcpb and can be uploaded through Smithery publishing.

Official MCP Registry

EngageLab Agent Email is also listed in the official MCP Registry. Clients that consume the Registry can find it by the server name io.github.Metaverse-Cloud/engagelab-email; the underlying npm package remains @engagelabemail/mcp.

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