Postal mail API for AI agents. mailbox.bot lets agents send outbound physical mail, including letters, certified mail, postcards, and batch mailings, with cost previews, approval controls, tracking, proof artifacts, and signed webhooks. It also supports inbound mail context from forwarded scans, phone-captured postal mail, PDFs, photos, and documents, so agents can understand physical-mail context and generate replies. Get a new receiving mailbox number for your agent with a real street-address opening soon through the mailbox.bot waitlist.