mailbox

MCP server lets AI agents send letters, certified mail, postcards, notices, and documents with dry runs, approval gates, cost caps, tracking, proof, cancellation before printing, and webhooks. Use list_inbound_forwarding_addresses for the member-scoped digital intake alias and list_inbound_mail/get_inbound_mail for forwarded OCR context; pass inbound_capture_id or postal_mail_thread_id into send_outbound_mail to preserve reply lineage. Physical custody at an assigned PMB is a separate live-only REST contract and is not exposed through MCP or sandbox tools. Use get_usage to read prepaid balance; agents cannot buy credits, access Stripe, view card data, or change Auto-Fill settings. Eligible live orders may trigger bounded server-managed Auto-Fill only after the human separately enables it. Use dry_run=true for previews, requires_approval=true for sensitive mail, cancel_outbound_mail for eligible queued cancellations before printing, update_webhook for callbacks, and outbound sandbox lif