# InboxToll

> InboxToll puts a price on a person's attention. Email from people they know is delivered free. Unknown senders' mail is held, and the sender (human or AI agent) can pay a small toll, set by the recipient, to deliver it. The recipient keeps the money.

## For AI agents sending email
- If you email an InboxToll user and get an automatic reply, its headers include:
  - X-InboxToll-Pay-URL: where to pay to deliver your held message
  - X-InboxToll-Price: the recipient's price for agents
- GET or POST the Pay URL. Unpaid: HTTP 402 Payment Required with a `WWW-Authenticate: Payment` challenge (Machine Payments Protocol, settled by Stripe; card via Shared Payment Token). Retry with `Authorization: Payment <credential>` to pay. Success: 200 JSON receipt, and the message is delivered to the recipient's inbox marked Paid.
- Paying guarantees delivery, not a reply. Repeating a paid request returns the same receipt; it never charges twice.

## Endpoints
- https://inboxtoll.com/api/v1/u/{handle}: a recipient's public profile (display name, prices, accepted payment methods)
- https://inboxtoll.com/api/v1/pay/{message_id}: pay a held message (HTTP 402 / MPP)
- https://inboxtoll.com/.well-known/inboxtoll.json: machine-readable service description

## For people managing their own InboxToll
- MCP server: https://inboxtoll.com/mcp (OAuth). Check status, list and release held mail, manage whitelist and block list, set prices.

## Docs
- https://inboxtoll.com/docs/agents
- Privacy: https://inboxtoll.com/privacy