Changelog

Agent payments, MCP parity, retention

quote_letter and send_letter (MCP) and POST /v1/quotes / POST /v1/orders (REST) accept an upload_key — quote or send a PDF you already uploaded via POST /v1/uploads without base64-encoding it through the call. Closes a real gap: a confirmation token only binds content the quote could see, so an agent that uploaded a PDF and only ever had text/pdf_url to quote with could never obtain authority to mail what it had uploaded.
send_letter (MCP) accepts credit_code — a funded agent can pay from a prepaid balance inside the tool call, with no payment_url and no human payment step. See Credits.
Idempotency keys are now scoped per caller (API key, else account, else IP), not globally — reusing a common key string ("1", today’s date) can no longer hand you back a stranger’s order id and its cancel/review tokens. See Send Policies.
New per-minute throttles on POST /v1/orders with sandbox: true (20/min) and POST /v1/credits/checkout (10/min) — both were reachable with no API key and no floor before. See Rate limits.
The document behind an order (the rendered PDF) is now actually deleted 30 days after delivery by an hourly job, not just documented as deleted — the retained record is metadata only. See Trust & data.

Docs + infra

Security round 2

Round 1

Launch

Live: send First-Class, Certified, Certified + e-Return Receipt, Priority mail online.
Prepaid credit codes (CARD-Act-compliant balances).
Content screening (fraud/threats only; lawful demand letters fine).