Mailbox
Send physical letters and certified mail from agent workflows for compliance notices, churn winbacks, or offline customer touchpoints.
Overview
bot.mailbox/mailbox is an MCP server for the Build phase that lets agents send physical letters and certified mail via mailbox.bot’s API.
What is this MCP server?
- Physical mail API: letters and certified mail callable via MCP
- Bearer auth supports agent keys (sk_agent_…), sandbox test keys (sk_agent_test_…), and member keys (sk_live_…)
- Sandbox mode for zero-charge production-endpoint testing
- Remote https://mailbox.bot/api/mcp; install docs at mailbox.bot/mcp-install; version 1.0.1
- MCP remote: https://mailbox.bot/api/mcp (streamable-http)
- Server version 1.0.1; schema 2025-12-11
- Key types: sk_agent_…, sk_agent_test_… (sandbox), sk_live_… (member)
What problem does it solve?
Agent-built products stall at digital-only channels when a workflow legally or practically requires paper mail and you have no simple API hook.
Who is it for?
Solo founders automating compliance, collections, or offline customer comms who want MCP-native physical mail with sandbox testing.
Skip if: Purely digital products with no postal requirement, or teams unwilling to manage Bearer secrets and real postage costs.
What do I get? / Deliverables
After registering MCP with a mailbox.bot key, your agent can queue real letters or certified mail—including sandbox test sends—without a separate fulfillment dashboard.
- Agent-triggered letter and certified-mail sends via mailbox.bot
- Sandbox-validated flows before spending on postage
- Offline touchpoints embedded in automated ops pipelines
Recommended MCP Servers
Journey fit
Build is the canonical phase because mailbox.bot is an external service you integrate when the product needs real-world mail, not when you are only drafting positioning. Integrations reflects the streamable-http MCP with Bearer agent, sandbox, or live member keys tied to mailbox.bot’s mail API.
How it compares
Physical-mail Communication MCP, not an email skill or a print-shop manual process.
Common Questions / FAQ
Who is bot.mailbox/mailbox for?
Builders shipping agent-driven ops, fintech, legal-tech, or support tools that must trigger real-world mail from Claude Code, Cursor, or similar clients.
When should I use bot.mailbox/mailbox?
Use it during Build when you integrate send-letter or certified-mail steps into workflows that agents execute autonomously or on behalf of users.
How do I add bot.mailbox/mailbox to my agent?
Mint a key at https://mailbox.bot/mcp-install, add remote MCP https://mailbox.bot/api/mcp with Authorization Bearer your key (sandbox sk_agent_test_… for test sends), then invoke mail tools from the agent.