google__adk-docs/docs/integrations/e2a.md

catalog_title, catalog_description, catalog_icon, catalog_tags

catalog_title	catalog_description	catalog_icon	catalog_tags
e2a	Authenticated email gateway for AI agents with human-in-the-loop approval	/integrations/assets/e2a.png	mcp

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. This integration gives your agent its own email inbox to send, receive, and reply to messages using natural language, with SPF/DKIM/DMARC verification on inbound mail and an optional human review hold on outbound messages.

The server is hosted at https://api.e2a.dev/mcp and speaks Streamable HTTP — there is nothing to install or run locally.

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 carries SPF, DKIM, and DMARC evidence, so your agent can tell whether the sender is who they claim to be before acting on the content.

• Human-in-the-loop review: Turn on a review hold and outbound messages are parked as pending_review until a human approves them — optionally with edits to the subject, body, or recipients before sending.

• Automate threaded conversations: Reply with In-Reply-To and References headers preserved, so threads stay intact across multiple turns in the recipient's mail client.

Prerequisites

• A free e2a account and an API key from the dashboard

Use with agent

=== "Python"

=== "Remote MCP Server"

    ```python
    from google.adk.agents import Agent
    from google.adk.tools.mcp_tool import McpToolset
    from google.adk.tools.mcp_tool.mcp_session_manager import (
        StreamableHTTPConnectionParams,
    )

    E2A_API_KEY = "YOUR_E2A_API_KEY"

    root_agent = Agent(
        model="gemini-flash-latest",
        name="e2a_agent",
        instruction=(
            "You manage email through the e2a tools. Call whoami once to "
            "learn your identity and inbox address. Use list_messages and "
            "get_message to read; use reply_to_message when replying to an "
            "existing thread (it preserves In-Reply-To and References), and "
            "send_message only to start a new thread. Both 'accepted' and "
            "'pending_review' are successful outcomes — never re-send after "
            "either one."
        ),
        tools=[
            McpToolset(
                connection_params=StreamableHTTPConnectionParams(
                    url="https://api.e2a.dev/mcp",
                    headers={"Authorization": f"Bearer {E2A_API_KEY}"},
                    timeout=30,
                ),
            )
        ],
    )
    ```

=== "TypeScript"

=== "Remote MCP Server"

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

    const E2A_API_KEY = "YOUR_E2A_API_KEY";

    const rootAgent = new LlmAgent({
        model: "gemini-flash-latest",
        name: "e2a_agent",
        instruction:
            "You manage email through the e2a tools. Call whoami once to " +
            "learn your identity and inbox address. Use list_messages and " +
            "get_message to read; use reply_to_message when replying to an " +
            "existing thread (it preserves In-Reply-To and References), and " +
            "send_message only to start a new thread. Both 'accepted' and " +
            "'pending_review' are successful outcomes — never re-send after " +
            "either one.",
        tools: [
            new MCPToolset({
                type: "StreamableHTTPConnectionParams",
                url: "https://api.e2a.dev/mcp",
                transportOptions: {
                    requestInit: {
                        headers: {
                            Authorization: `Bearer ${E2A_API_KEY}`,
                        },
                    },
                },
            }),
        ],
    });

    export { rootAgent };
    ```

!!! tip "For production, pair the toolset with the e2a SDK"

The MCP toolset hands the inbox to the model. Keep the deterministic
parts — verifying webhook signatures, handling at-least-once delivery,
sending idempotently — in application code with the
[Python](https://pypi.org/project/e2a/) or
[TypeScript](https://www.npmjs.com/package/@e2a/sdk) SDK. The ADK webhook
example below is a complete working version of that shape.

Available tools

The hosted server exposes 60+ tools; call tools/list against the endpoint for the authoritative set. Which ones you see depends on your key: an agent-scoped key (e2a_agt_…) — recommended for a deployed agent — sees only the runtime tools, while an account-scoped key (e2a_acct_…) also sees the admin tools below.

Runtime — inbox tools

Tool	Description
whoami	Return the authenticated identity: user, credential scope, plan and usage limits, plus agent_email for an agent-scoped credential
get_agent	Fetch one agent's full record
list_messages	List inbox or sent mail with direction, read_status, search filters, and cursor pagination
get_message	Full body, headers, attachment metadata, and SPF/DKIM/DMARC evidence for one message
get_message_lifecycle	Reconstructed delivery history for one message
get_attachment	Attachment metadata, or the bytes inline with inline: true
send_message	Send a new email; returns accepted, or pending_review when a review hold catches it — both are success, neither should be retried
reply_to_message	Reply in-thread; preserves In-Reply-To and References
forward_message	Forward a message to new recipients
list_conversations / get_conversation	Browse threads rather than individual messages
update_message_labels	Add or remove labels on a message
delete_message / restore_message	Soft-delete to trash, and restore

Admin — provisioning and setup

Tool	Description
list_agents, create_agent, update_agent, delete_agent, restore_agent	Manage agent inboxes
get_protection, update_protection	Per-agent screening and review-hold configuration
list_domains, register_domain, get_domain, verify_domain, delete_domain	Custom domain registration and DNS verification
list_reviews, get_review, approve_review, reject_review	Work the human review queue
list_webhooks, create_webhook, update_webhook, delete_webhook, rotate_webhook_secret, test_webhook, list_webhook_deliveries	Webhook subscriptions and delivery history
list_events, get_event, redeliver_event	Event log and replay
list_templates, create_template, update_template, delete_template, validate_template	Server-side email templates (beta)
list_api_keys, create_api_key, delete_api_key	API key management

Configuration

The hosted endpoint needs no environment variables beyond your API key, which ADK passes in the Authorization header shown above. To use a self-hosted e2a deployment, change the url to that deployment's /mcp endpoint.

Interactive MCP clients can add https://api.e2a.dev/mcp as an OAuth 2.1 connector instead of pasting a key. To receive mail, poll list_messages, open a WebSocket with the SDK's listen() (no public URL required), or subscribe an HTTPS endpoint with create_webhook.

Additional resources

• e2a MCP Server source
• Runnable ADK example
• ADK webhook example
• e2a documentation