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Mail letters with an API
Yes, you can mail letters with an API using PostalForm. Create an order draft from a PDF, launch checkout, and we print and mail the letter via USPS.
Published Jan 20, 2026
How it works
Step 1
Upload a PDF
Create an upload and send the file.
Step 2
Create an order draft
Provide sender and recipient addresses plus print options.
Step 3
Start checkout
Use the returned checkout URL.
Step 4
Track status
Check order status after payment.
Good fits for the API
- Automated mailings from internal tools
- Transactional letters like invoices and notices
- Mailings generated from case management systems
- Agent or MCP-based workflows
Ready to build?
Start with the developer guide and sample requests. Go to developers
FAQs
- Do you offer an API for mailing letters?
- Yes. PostalForm exposes an MCP server at /mcp for order drafts, uploads, and status.
- Can I send from my own app?
- Yes. Use the API to create drafts and send users to checkout.
- Can I control print options?
- Yes. Set color, duplex, and delivery speed on the draft.
- Do you support Certified Mail?
- Yes. Certified Mail is available with First Class.