Do you actually print and mail letters?

Yes. Live fulfillment is designed for LetterStream. This deployment runs in demo mode until LetterStream credentials are confirmed, so you can send mock letters end-to-end without purchasing postage.

Can an AI agent send mail?

Yes. Use the REST API with an API key, or connect the MCP server in Claude or Cursor. Agents can pay with x402 and USDC.

What mail classes are supported?

USPS First-Class letters, Certified Mail with optional Electronic Return Receipt, and 4×6 postcards.

Print and mail · API · MCP · x402

Send a real letter.From a browser, an app, or an agent.

LettersByLetter is the modern way to put paper in the mail. Compose or upload a PDF, choose First-Class, Certified, or a postcard, and we print and mail it. Pay with card or USDC.

Send a letter Read the docs

Demo mode is on until Firebase and LetterStream are configured. No postage is purchased.

Cream envelope with a letter peeking out

How it works

Compose

Upload a PDF or write a short letter. Save addresses from the send screen. CSV lists go through the API.

Choose mail

First-Class, Certified with optional ERR, or a 4×6 postcard. Live price as you go.

We mail it

LetterStream prints and enters the USPS stream. Track the job from your dashboard or API.

Built for operators and agents

PDF or compose

Drop a finished PDF or write the letter in the wizard.

Address book

Save senders and recipients from the send screen. CSV via the API.

Certified + ERR

Legal-grade mail class with electronic return receipt.

Staging + live keys

lbl_test_ never mails. lbl_live_ does when the app is live.

First-class MCP

send_letter, status, jobs, and pricing tools for Claude and Cursor.

Cards + USDC

Square for cards. HTTP 402 / x402 for USDC on Base or Solana.

Transparent per-piece pricing

First-Class $1.49, Certified $12.99, postcards $1.99. Extra letter pages are $0.25. No subscription required.

See pricing

First-Class

$1.49

page 1 · +$0.25 extra pages

Certified

$12.99

base piece · +$0.25 extra pages

Postcard

$1.99

4×6 color, flat

Questions, answered

Do you actually print and mail letters?: Yes. Live fulfillment is designed for LetterStream. This deployment runs in demo mode until LetterStream credentials are confirmed, so you can send mock letters end-to-end without purchasing postage.
Can an AI agent send mail?: Yes. Use the REST API with an API key, or connect the MCP server in Claude or Cursor. Agents can pay with x402 and USDC.
What mail classes are supported?: USPS First-Class letters, Certified Mail with optional Electronic Return Receipt, and 4×6 postcards.

Put something in the mail today.

Open the demo workspace, send a mock letter, mint an API key, and wire MCP in a few minutes.

Enter the workspace