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ReceiveHQ
ReceiveHQ

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Let your agent receive email when it needs to

#mcp #agents #email #webhooks

I'm Sebastian, CTO at ReceiveHQ (Cortena B.V.). This is a concrete walkthrough of one feature we use ourselves: giving Cursor or Claude a real inbound mailbox over MCP, without waiting for a webhook handler to exist.

The problem

Agent workflows often need email mid-task: a vendor sends a confirmation, a support reply lands, a magic link arrives, or you want the agent to triage overnight mail. Most inbound products assume you already have a public HTTPS endpoint and a parser wired up. Agents don't.

Blackhole first, webhook later

ReceiveHQ endpoints come in two kinds:

Kind URL What happens
  1. Create an account at https://receivehq.com (magic-link sign-in).
  2. Add the MCP server to your client: 
{
  "mcpServers": {
    "receivehq": {
      "url": "https://receivehq.com/api/mcp"
    }
  }
}
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  1. Start the client — OAuth 2.1 + PKCE opens a browser for login and consent.
  2. Revoke apps anytime under Settings → MCP in the console.

Endpoint docs live at https://receivehq.com/mcp.md (also /llms.txt).

Agent quick start

From Cursor, Claude, or another MCP client:

  1. Run setup_inbound_domain with endpointKind: "blackhole" (no endpointUrl), or create the domain then create_inbound_domain_endpoint.
  2. Point MX to mx.receivehq.com, then verify_inbound_domain_mx.## What else the agent can do
  • Tenants, domains, and endpoints (CRUD)
  • Search messages, inspect delivery attempts, resend
  • Invite teammates
  • Billing: Checkout / Customer Portal URLs
  • Fetch retained attempt and raw-mail objects by key (14-day evidence window)

Scopes: mcp:read for reads, mcp:admin for mutations. Tokens are user-scoped across that user's tenants.

Why this beats "paste the email into chat"

  • Real SMTP address on your domain (or a ReceiveHQ receive domain)
  • MIME parsed once; raw .eml retained for support and compliance
  • Same account can later fan out to webhooks without re-ingesting history
  • Hosted in Germany (Hetzner); DPA / sub-processors / hosting / imprint are public for GDPR buyers

Try it

  1. Sign up: https://receivehq.com
  2. Connect MCP: https://receivehq.com/api/mcp
  3. Create a blackhole endpoint and send yourself a test message
  4. Ask the agent to list_messages

Pricing: €10/mo or €100/yr for up to 100k inbound emails; first 10 free per tenant.

Trust links: hosting · DPA · sub-processors · imprint

  1. Read mail with list_messages / get_message / list_deliveries.

When you are ready for production delivery, create or update an endpoint as webhook with your URL and payloadFormat (postmark, Mailgun/SendGrid, or CloudMailin). Same mailbox, no DNS redo.

| blackhole | omit / empty | Mail is received, parsed, and stored. Delivery status is blackholed. No HTTP forward. Works on trial. |
| webhook | required HTTPS | Same parse, then POST in Postmark / Mailgun-SendGrid / CloudMailin shape |

Blackhole is the agent-friendly path: capture mail now, decide routing later.

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