LettrLabs API

Creating an Order

Generate a direct‑mail order from a template and send it to your recipients.

An order is a batch of direct mail generated from one of your templates and addressed to a set of recipients. You create orders with a single call to POST /v1/order, referencing a template you have already designed in the LettrLabs app.

Before you start

  • A public API key — see Authentication & API keys.
  • A template built in the LettrLabs app. Its numeric template ID is what you pass as templateId.

Create an order from a template

The only required field is templateId. The full request body — recipients, mailing options, and template merge fields — is documented, field by field, on the POST /v1/order reference page, where you can also fire the request live with your own key.

curl -X POST https://app.lettrlabs.com/api/v1/order \
  -H "X-API-KEY: your_api_key_here" \
  -H "Content-Type: application/json" \
  -d '{
    "templateId": 12345
  }'

A successful call returns the created order. Keep the returned order ID — you use it to manage recipients, pull proofs, and check out the order.

Work with an order after it's created

Each of these is documented in full under API Reference:

ActionEndpoint
List ordersGET /v1/order
Review an order's recipientsGET /v1/order/{id}/recipients
Add or update recipientsPUT /v1/order/{id}/recipients
Remove recipientsDELETE /v1/order/{id}/recipients
Preview a proofGET /v1/order/{id}/proof
Check out (confirm + pay)POST /v1/order/{id}/checkout
Cancel an orderDELETE /v1/order/{id}

Idempotency

Re‑sending the same POST /v1/order request creates a new order each time — there is no automatic de‑duplication. If a request times out, fetch GET /v1/order to check whether the order was created before retrying, so you don't mail the same batch twice.

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