SuperMailOS
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AI agents & API

Let your AI assistant work your mail. Only as far as you allow.

An MCP server, a REST API and signed webhooks, on every plan. Claude and ChatGPT connect with a sign-in; Claude Code, Codex and Cursor with an API key. Start read-only, draft before you send, and allow sending only if you choose.

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Included on every plan. See all features

Setup for each client is in the MCP docs; endpoints and samples in the API reference.

01 What you get

Your mail, open to your tools, closed to everyone else.

The MCP server and the REST API run the same operations, with the same permissions, access rules and rate limits.

MCP server, 13 tools

Over Streamable HTTP at https://supermailos.com/mcp. Read: list_mailboxes, search_mail, list_threads, get_thread, get_message, get_attachment. Manage: mark_read, archive_thread, move_thread, label_thread, draft_reply. Send: reply_to_thread, send_email.

Three permissions

Read mail: Mailboxes, threads, messages, attachments and search. Manage mail: Mark read, star, archive, move, label and save reply drafts. Never sends. Send mail: Send a new email and reply to a conversation. Tools a connection isn't allowed are hidden from it.

Drafts before sends

draft_reply saves a draft you review and send yourself. reply_to_thread and send_email send straight away; sends take an idempotency key (required over MCP), so a retry never sends twice.

The inbox's guardrails

Sending through the API or MCP passes the same checks as the app: a verified domain, the suppression list, hourly limits and new-domain warm-up. Bcc stays as private as it is in the inbox.

REST API with an OpenAPI spec

120 requests a minute per key, JSON errors, an OpenAPI 3.1 document at /api/v1/openapi.json, and samples in curl, TypeScript and Python.

Signed webhooks

A signed POST (HMAC-SHA256) to your URL when mail arrives, is sent, is delivered, bounces or draws a complaint, with retries.

02 How it works

Connected in three steps.

Nothing to install: one URL and a sign-in, or an API key.

01Connect your assistant

In Claude or ChatGPT, add https://supermailos.com/mcp as a connector and sign in. Elsewhere, a workspace admin creates an API key in Settings → Developers and puts it in the client's Authorization header.

02Choose what it may do

Approve only the permissions it needs: reading, managing mail, sending. You can revoke the connection or the key at any time.

03Ask in plain words

“Find last week's invoice from Acme and draft a reply.” The assistant lists your mailboxes, searches, reads the thread and leaves a draft for you.

03 Questions

Agent questions, answered.

Something else? Write to us — a real person answers, usually the same day.

Talk to us
Which AI assistants can connect?+
Claude (claude.ai, the desktop and mobile apps) and ChatGPT connect with a sign-in: add https://supermailos.com/mcp as a connector, sign in and approve. Claude Code, Codex, Cursor and any MCP client that can set an Authorization header connect with an API key.
Can an assistant send email without asking me?+
Only if its connection has the "Send mail" permission. Without it, the sending tools are hidden from the assistant. draft_reply only saves a draft for you to review and send yourself.
Which mailboxes can an assistant see?+
Only the ones the person who created the key, or approved the connection, can open in the app. Each assistant can have its own key with the fewest permissions it needs, and you can revoke it at any time.
Is it on every plan?+
Yes. The REST API, webhooks and the MCP server are included on every plan, at no extra cost.
Is SuperMailOS in the MCP Registry?+
Yes, as com.supermailos/mail in the official MCP Registry, pointing at the same server URL.

Give your assistant
an inbox it can use.

Every domain in one inbox, with an MCP server, API and webhooks on every plan. 14 days free, no card.

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