Observed arrival · 2026-09-10

LettersByLetter Puts APIs in the Postal Stream

lettersbyletter.com Observed source

Editorial interest 84/100 Selection signal · not a rating of the site

A print-and-mail service for USPS letters, Certified Mail, and 4×6 postcards, with REST, MCP, and x402 access for developers and agents.

Landing page captured for the 2026-09-10 issue.

Field notes

The service separates composition from fulfillment: a user or integration supplies a letter or PDF, selects a USPS class, and receives dashboard or API tracking after LetterStream handles printing and entry into the mail stream. Its developer surface includes REST, OpenAPI, hosted MCP for Claude or Cursor, and x402 payments in USDC on Base or Solana. Listed prices are $1.49 for a first First-Class page, $12.99 for Certified Mail, and $1.99 for a 4×6 postcard.

Observed signals

Read the marks

Editorial observations of this landing page, not a rating.

○OpenPublic substance visible

$PaidCommerce or pricing visible

✦PrettyNotable craft visible

●ProPolished or operationally mature

◎NicheUnusually specific use

ƒJavaScriptBrowser-side code central

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