Skip to content

e2a MCP tool for ADK

Supported in ADKPythonTypeScript

The e2a MCP Server connects your ADK agent to e2a, an authenticated email gateway built for AI agents. Inbound mail is SPF/DKIM-verified before it reaches your agent. Outbound mail can be held for human approval before it ships.

Use cases

  • Give agents their own inboxes: Provision dedicated email addresses (e.g. support-bot@your-domain.com) and let agents send and receive mail just like a teammate.

  • Authenticated inbound: Every incoming message arrives with SPF and DKIM verification results so your agent knows whether the sender is who they claim to be.

  • Human-in-the-loop approval: Configure HITL on any agent and outbound messages are held in a pending queue until a reviewer approves them — optionally with edits to subject, body, or recipients before sending.

  • Automate threaded conversations: Reply to received emails with proper In-Reply-To and References headers preserved, so threads stay intact across multiple turns.

Prerequisites

  • A free e2a account and an API key from the dashboard.
  • Node.js 18+ on the machine running the agent (the MCP server is distributed via npx -y @e2a/mcp-server).

Use with agent

from google.adk.agents import Agent
from google.adk.tools.mcp_tool import McpToolset
from google.adk.tools.mcp_tool.mcp_session_manager import StdioConnectionParams
from mcp import StdioServerParameters

E2A_API_KEY = "YOUR_E2A_API_KEY"
E2A_AGENT_EMAIL = "your-bot@your-domain.com"  # optional default inbox

root_agent = Agent(
    model="gemini-flash-latest",
    name="e2a_agent",
    instruction=(
        "You manage email through the e2a tools. Call whoami once "
        "to find your inbox address. Use list_messages and "
        "get_message to read; use reply_to_message (not "
        "send_email) when replying to an existing thread so "
        "threading headers are preserved."
    ),
    tools=[
        McpToolset(
            connection_params=StdioConnectionParams(
                server_params=StdioServerParameters(
                    command="npx",
                    args=["-y", "@e2a/mcp-server"],
                    env={
                        "E2A_API_KEY": E2A_API_KEY,
                        "E2A_AGENT_EMAIL": E2A_AGENT_EMAIL,
                    },
                ),
                timeout=30,
            ),
        )
    ],
)

import { LlmAgent, MCPToolset } from "@google/adk";

const E2A_API_KEY = "YOUR_E2A_API_KEY";
const E2A_AGENT_EMAIL = "your-bot@your-domain.com"; // optional default inbox

const rootAgent = new LlmAgent({
    model: "gemini-flash-latest",
    name: "e2a_agent",
    instruction:
        "You manage email through the e2a tools. Call whoami once " +
        "to find your inbox address. Use list_messages and " +
        "get_message to read; use reply_to_message (not " +
        "send_email) when replying to an existing thread so " +
        "threading headers are preserved.",
    tools: [
        new MCPToolset({
            type: "StdioConnectionParams",
            serverParams: {
                command: "npx",
                args: ["-y", "@e2a/mcp-server"],
                env: {
                    E2A_API_KEY: E2A_API_KEY,
                    E2A_AGENT_EMAIL: E2A_AGENT_EMAIL,
                },
            },
        }),
    ],
});

export { rootAgent };

Available tools

Identity

Tool Description
whoami Return the default agent's full record (requires E2A_AGENT_EMAIL)
list_agents List every agent inbox owned by the authenticated user
create_agent Register a new inbox using a slug on the shared domain; defaults to local mode so the agent receives mail by polling — no webhook required

Cloud-mode agents must verify webhook signatures

When you create an agent with agent_mode: "cloud", e2a HMAC-signs every webhook delivery against your account's webhook signing secret (E2A_WEBHOOK_SECRET, shown in the e2a dashboard). Your webhook handler must verify the signature on every request — the e2a SDK exposes parseWebhook(body, secret) which parses and verifies in one call. Local-mode agents (the default) avoid this entirely by polling via list_messages. A complete runnable cloud-mode + ADK example with proper signature verification lives at github.com/Mnexa-AI/e2a/tree/main/examples/adk-cloud-webhook.

Messages

Tool Description
send_email Send a new email; returns status: pending_approval instead of sent when HITL is enabled
reply_to_message Reply to an inbound message; preserves In-Reply-To and References headers
list_messages List inbound mail with status filter (unread / read / all) and pagination
get_message Fetch full body, headers, and attachment metadata for one message

Human-in-the-loop approval

Tool Description
list_pending_messages List outbound mail awaiting human approval, soonest-expiring first
get_pending_message Get the full draft (subject, recipients, body) of a pending message
approve_pending_message Send a held message, optionally with reviewer edits (subject / body / recipients)
reject_pending_message Discard a held message; optional reason stored for audit

Configuration

Variable Required Default Description
E2A_API_KEY Yes — Your e2a API key
E2A_AGENT_EMAIL No — Default agent inbox; scopes tools so the LLM doesn't repeat the address on every call
E2A_BASE_URL No https://e2a.dev Self-hosted deployment URL

Additional resources