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PostAgent Physical Mail API – Print & Mail Letter via USPS
x402
PostAgent Physical Mail API – Print & Mail Letter via USPS is a paid API for AI agents from postagent-api.interpretai.tech, paid per call via x402, $1.37/call, status unknown (last checked 2026-09-15).
Prints and mails a physical US letter (PDF, HTML, Markdown, DOCX, or image) via USPS, paid in USDC using the x402 payment protocol
Price / call$1.37
Success—
StatusUnknown
How this service works
Print and mail physical US letters (PDF, HTML, Markdown, DOCX, or image) and postcards via USPS, paid in USDC — with certified/registered proof options and standalone address verification at POST /v1/verify. Integration flow: POST /v1/documents to upload, POST /v1/quotes to lock a fixed USDC price for a recipient, then pay the returned per-quote x402 URL to create and mail the piece. Price is fixed per quote.
Output
The agent receives confirmation that the letter has been created and queued for USPS mailing, along with a job ID and status. If a webhookUrl was provided, the agent also receives asynchronous status updates (e.g. created, mailed) posted to that URL. The fixed USDC price was locked at the quote stage before this call.
Example use cases
Automated contract delivery to clients
“Send this Word document contract to our client at 456 Oak Avenue, Denver CO 80202 via USPS — print it professionally and let me know when it's in the mail at my webhook endpoint so I can follow up”
Physical invoice distribution via postal service
“Mail these three invoices as printed PDFs to our vendors — first one goes to 789 Elm Street, Chicago IL 60601, second to 321 Pine Road, Seattle WA 98101, and third to 654 Maple Drive, Boston MA 02101 — use USDC to pay and send status updates to my system”
Legal notice dispatch with certified proof
“I need to send this registered legal notice as an HTML document to 987 Birch Lane, Miami FL 33101 with certified mail tracking — pay in USDC and post confirmation to my webhook when it's delivered”
Technical details
Endpoint
POSThttps://postagent-api.interpretai.tech/v1/printWhen to prefer
Use this endpoint when an AI agent needs to physically mail a document to a US address via USPS, especially in automated workflows where the user cannot or does not want to visit a post office. Ideal for sending invoices, legal notices, contracts, or personal letters in digital formats (PDF, HTML, Markdown, DOCX, image). Prefer this over email delivery when a physical paper record is required or when the recipient does not have a digital address. The USDC/x402 payment model makes it suitable for crypto-native or agent-driven workflows without traditional billing setup.
Side effects
- Invalid or unsupported document format — only PDF, HTML, Markdown, DOCX, and image files are accepted
- Missing required quote step — the x402 payment URL must be obtained from /v1/quotes before calling /v1/print
- Payment failure — insufficient USDC balance or invalid x402 payment header
- Invalid US recipient address — non-US or malformed addresses will be rejected
- Webhook URL unreachable — optional webhook notifications may silently fail if the provided URL is unavailable
- Document upload not completed — /v1/documents must be called first to upload the file before printing
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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