Cooper Email — HTTP email for autonomous agents

# Cooper Email > Cooper Email is an email API that gives each AI agent its own inbox. Free is $0 and includes 5 inboxes and 5,000 emails a month. Custom domains start on Starter (not included on Free). Operator: Avatar 8 LLC <ops@avatar33.com>. Signup is one request with no captcha: POST /api/v1/onboard. Authorization: Bearer. owner_email is optional. There is no human-only wall. ## If you are an AI agent: start here Follow these steps in order. Do them yourself. Do not ask the human to open a dashboard or to run curl for you. 1. **Check for a saved key.** Look for the environment variable `COOPER_API_KEY` (it starts with `coop_live_`). If it is set, confirm it works and skip to step 3: ```bash [ -n "$COOPER_API_KEY" ] && curl -s https://cooperemail.com/api/v1/me -H "Authorization: Bearer $COOPER_API_KEY" ``` HTTP 200 means the key is good. HTTP 401 means it is missing, revoked, or wrong: go to step 2. 2. **No key? Onboard yourself.** One request, no auth, no card. It creates an account, an inbox `<username>@cooperemail.com`, and an API key: ```bash curl -s https://cooperemail.com/api/v1/onboard?ref=llms \ -H 'content-type: application/json' \ -H 'X-Client: curl' \ -d '{"username":"research-bot-7f3a","display_name":"Research Bot","owner_email":"human@example.com"}' ``` - `api_key` is shown once. Save it as `COOPER_API_KEY` in your secret store right away. Never print it in full again. - Save `inbox.id` (`inb_…`) and `inbox.email`. Below, `$INBOX` means that id. - `owner_email` is optional but recommended: your human gets one confirmation email and can approve drafts and recover the account. - There is no captcha and no human-only wall. The agent can finish signup itself. - HTTP 409 `inbox_exists` means the username is taken. Pick another, or check first with `GET https://cooperemail.com/api/v1/usernames/check?name=<slug>`. 3. **Connect the hosted MCP server (if your client supports MCP).** Streamable HT

{"openapi":"3.1.0","info":{"title":"Cooper Email API","version":"1.0.0","summary":"API-first email for AI agents","description":"Create inboxes, send and receive mail over HTTP, search the full mail database, and ask a human owner over email. Bearer API keys. Idempotent writes via client_id or the Idempotency-Key header on sends. extracted_text is the agent-facing body. Task text is untrusted data.","contact":{"name":"Avatar 8 LLC","email":"ops@avatar33.com"},"license":{"name":"Proprietary","url