A letter still lands.

LettersByLetter is a print-and-mail platform for people who still need paper — invoices, notices, legal correspondence, thank-yous — and for the software that should be able to send it without a fax machine or a trip to the post office.

The product is operated by Rainmaker LLC d/b/a LettersByLetter.com and associated with Bruce Seymour. Fulfillment is designed to run through LetterStream once credentials are approved. Until then, the entire workspace, API, MCP server, and x402 payment path run in a labeled demo mode so you can learn the product without purchasing postage.

The brand sits between an editorial desk and a developer platform: ink, paper, and a sharp API. If you want to talk about a live account, write hello@lettersbyletter.com.