AI agents & API
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.
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
The MCP server and the REST API run the same operations, with the same permissions, access rules and rate limits.
Over Streamable HTTP at https://supermailos.com/mcp. Read: list_mailboxes, search_mail, list_threads, get_thread, get_message, get_attachment, list_agent_inboxes, list_agent_approvals, list_held_mail, list_domains, get_domain, check_domain. Manage: mark_read, archive_thread, move_thread, label_thread, draft_reply, create_agent_inbox, update_agent_inbox, decide_held_mail, add_domain. Send: reply_to_thread, send_email, decide_agent_approval.
Read mail: Mailboxes, threads, messages, attachments and search. An owner's or admin's key also sees the workspace's domains and checks their DNS. Manage mail: Mark read, star, archive, move, label and save reply drafts. Never sends. An owner's or admin's key also adds domains and creates agent inboxes. Send mail: Send a new email and reply to a conversation. Tools a connection isn't allowed are hidden from it.
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.
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.
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.
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
Nothing to install: one URL and a sign-in, or an API key.
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.
Approve only the permissions it needs: reading, managing mail, sending. You can revoke the connection or the key at any time.
“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 Agent inboxes
An agent gets its own address on your domain, next to your team, with a person who answers for it and guardrails on from the start. See agent inboxes
01
An address like billing@ on your verified domain, with a named person who answers for it. You see its mail in the app, and its key reaches that one inbox.
02
Replies, and email to people it already writes with, go out on their own. An email to someone new waits until a person approves it.
03
Mail whose sender fails authentication doesn't reach the agent until a person releases it. What it does read is the visible text, with hidden text stripped out.
04
Every email it sends ends with a line saying an AI agent sent it, and on whose behalf.
05
Complaints or bounces on its mail pause that agent alone. Everyone else in your workspace keeps sending.
06
Agent inboxes never count as paid seats. Each paid seat includes 2 on Pro and 5 on Business, and the 14-day trial includes 3.
04 Questions
Something else? Write to us — a real person answers, usually the same day.
Every domain in one inbox, with an MCP server, API and webhooks on every plan. 14 days free, no card.