Machine Inbox Stripe MPP example

The live service charges through Stripe Machine Payments Protocol (MPP): $2.00 USD for a seven-day inbox, $5.00 for a thirty-day pro inbox (500 messages, 100 MiB, 50 replies per day), and $1.00 to extend an active inbox seven more days. Every purchase includes authenticated replies under the published limits.

Stripe Link CLI

  npx @stripe/link-cli mpp pay https://machineinbox.com/api/v1/inboxes \
    --context "Create one seven-day Machine Inbox for an automated task"

The client handles the HTTP 402 WWW-Authenticate challenge, obtains a Stripe Shared Payment Token, retries with Authorization: Payment, and prints the successful response. That response contains the inbox ID, address, expiry, and mailbox bearer token. Store the token as a secret.

For reliable application retries, send a unique Idempotency-Key on the initial request and reuse it on the paid retry. The official `mppx validate` command can call this endpoint without that application-specific header; Machine Inbox binds a generated key into the MPP challenge in that case.

Files in this directory

  create-inbox.ts     Buy an inbox with the Stripe Link CLI (also create_inbox.py)
  raw-402-flow.txt    The exact HTTP 402 challenge and paid retry, header by header
  read-reply-loop.ts  Post-purchase loop: list, read, reply, poll delivery (also read_reply_loop.py)
  extend-inbox.ts     Extend an active inbox by seven days for $1.00

Validation

  npx mppx@latest validate https://machineinbox.com

The Stripe MPP guide is at https://docs.stripe.com/payments/machine/mpp