arbengine/mailbox-mcp

Official hosted Model Context Protocol server for **mailbox.bot**. Production is remote Streamable HTTP at https://mailbox.bot/api/mcp.
Agents send letters, certified mail, postcards, and document packets. mailbox.bot prints, stamps, mails, photographs, tracks, and returns proof. Agent mailboxes are live now: a real street address plus PMB at the staffed, USPS-compliant Manhattan Beach, CA facility, **$15/mo**. The PMB number is assigned after USPS Form 1583 verification. The online notary fee is waived. Outbound mail uses prepaid credits and has no monthly base fee.
- **Website:** https://mailbox.bot
- **Install:** https://mailbox.bot/mcp-install
- **Pricing:** https://mailbox.bot/pricing
- **Public tool catalog:** https://mailbox.bot/api/mcp/tools-public
- **OpenAPI:** https://mailbox.bot/openapi.json and https://mailbox.bot/openapi.yaml
- **Registry:** bot.mailbox/mailbox (DNS-verified on mailbox.bot)
Connect
Add the hosted URL to the MCP client and pass a bearer key. Customers do not run a local process.
Create an account at mailbox.bot/signup. A live agent key (sk_agent_) sends real mail and spends prepaid credits. A sandbox key (sk_agent_test_) rehearses on the same endpoint with no charge and no physical mail. A member account key (sk_live_) cannot send mail.
Pricing
| Plan | Price | What you get |
|---|---|---|
| Outbound mail and forwarded inbound context | $0/mo | Print and mail with prepaid credits. Forward scans, photos, and PDFs from an address you already control. |
| Mailing address | $15/mo | Street address plus PMB at the Manhattan Beach, CA facility. Live now. The PMB number is assigned after USPS Form 1583 verification. |
Published outbound examples start at $2.00 for a 1-page USPS First-Class letter. A dry run returns the exact price for that document, page count, service, and ZIP. That cost_breakdown is the price that applies.
Tools
45 hosted tools. Current tools are listed first. A deprecated tool is still served and names its replacement. Live schemas: public catalog.
| Tool | Description |
|---|---|
| get_mailbox | Read the account mailing address: street address plus PMB at the Manhattan Beach, CA facility. The rental is $15/mo and mailboxes are live now. The PMB number is assigned after USPS Form 1583 verification. |
| get_usage | Read usage events and the prepaid credit balance. Agents can read the balance and cannot buy credits. |
| list_inbound_forwarding_addresses | List the member's intake aliases on forward.mailbox.bot for scans, photos, and PDFs from an address the operator already controls. |
| list_inbound_mail | List forwarded inbound mail with compact draft context for a reply. |
| get_inbound_mail | Read one forwarded inbound item, OCR-backed facts, reply hints, and thread linkage. |
| list_postal_threads | List physical-mail threads that group inbound context and outbound sends. |
| get_postal_thread | Read one physical-mail thread and its timeline. |
| get_mailbox_md | Read this agent's versioned MAILBOX.md instructions before an outbound send. |
| propose_mailbox_md_edit | Propose an edit to standing instructions. The owner accepts or rejects it. |
| send_facility_message | Send a message to the facility handling this mailbox. |
| list_facility_conversations | List conversations with the facility. |
| get_facility_messages | Read messages in a facility conversation. |
| update_webhook | Update the legacy agent webhook callback URL and event subscriptions. |
| send_outbound_mail | Print and mail a document with prepaid credits. Call with dry_run=true and show the price before a live send. |
| list_outbound_mail | List outbound mail jobs and their status. |
| get_outbound_mail | Read one outbound job, including cost, status, and fulfillment photos. |
| cancel_outbound_mail | Cancel queued mail before printing and return eligible prepaid credits once. |