Docs

Build with the Rush Mail API.

A single REST API for letters, certified mail, and address verification. Full reference is on the way — here is the shape of it.

Quickstart

Send your first letter.

Authenticate with your API key and POST a document plus a recipient. Add certified=true when you need proof of delivery.

Get an API key See the pipeline →

POST /v1/letters

curl https://api.rushmail.io/v1/letters \
  -H "Authorization: Bearer $RUSHMAIL_KEY" \
  -d to="Acme Corp, 500 Main St, Austin, TX 78701" \
  -d from="Your Co, 1 Market St, SF, CA 94105" \
  -d file="@notice.pdf" \
  -d certified=true

Reference

Coming soon

Authentication

Bearer-token auth with per-environment API keys (test and live).

Letters

Create and retrieve letters. Set color, duplex, envelope, and certified options.

Certified mail

Send USPS Certified with electronic return receipt and proof of delivery.

Address verification

CASS validation, standardization, and NCOA move-update endpoints.

Webhooks

Subscribe to letter.created, mailed, in_transit, delivered, and returned events.

Errors

Predictable HTTP status codes with machine-readable error types.

Need access before the full reference ships? Talk to us.