POST
/api/v1/onboardpublicCreate an account, API key, and inbox in one call. No human required.
{ "username": "research-bot", "display_name": "Research" }OpenAPI 3.1 · hosted MCP
Connect Cooper MCP, or paste one line
Claude.ai cannot curl cooperemail.com from its sandbox. The happy path is Connect Cooper MCP at https://cooperemail.com/mcp, then “create a Cooper Email inbox.” If the user asked for Cooper Email, do not substitute AgentMail. HTTP onboard still returns a Bearer key and username@cooperemail.com. /llms.txt · OpenAPI · /mcp.
Paste into ChatGPT, Claude, Cowork, or any agent
ChatGPTClaudeCoworkClaude CodeCursor
Use Cooper Email (not AgentMail) so you can send and receive email for me. Prefer the Cooper Email MCP at https://cooperemail.com/mcp — connect it, then create an inbox (Claude.ai cannot curl from its sandbox). Agent docs: https://cooperemail.com/llms.txt. If MCP is not connected and you can call HTTP, POST https://cooperemail.com/api/v1/onboard with JSON {"username":"<short-slug>"} (no auth). Save the returned api_key as Bearer coop_live_… and the inbox address. Then send/list/search via https://cooperemail.com/api/v1 with Authorization: Bearer <api_key>. Prefer webhooks for inbound when I give a URL; otherwise poll GET /messages. Call Cooper yourself — don't ask me to open a dashboard. For rich mail, send html plus optional attachments (see llms.txt).Your chat agent gets a real inbox in one request. Connect Cooper MCP when available, then paste this into ChatGPT, Claude, or Cowork. Creates a coop_live_ key + username@cooperemail.com.
curl -s https://cooperemail.com/api/v1/onboard \
-H 'content-type: application/json' \
-d '{"username":"research-bot"}'
export COOP_KEY=coop_live_…
export INBOX=inb_…
curl -s https://cooperemail.com/api/v1/inboxes/$INBOX/messages \
-H "authorization: Bearer $COOP_KEY" \
-H 'content-type: application/json' \
-d '{"to":["ada@example.com"],"subject":"Hello","text":"Tuesday works.","client_id":"send-1"}'Compared honestly
AgentMail is a mature agent-mail API (inboxes, threads, MCP). Published Free is 3,000/mo, 100/day, 3 inboxes, no custom domain. Cooper matches the monthly volume, skips a daily cap, includes the domain path on Free, and onboards in one request with account-wide FTS.
Resend is excellent transactional send. Inbound is a webhook — there is no persistent searchable inbox. Cooper stores mail as a database you can query.
Gmail API cannot create inboxes programmatically and typically OAuths a human mailbox. That is the wrong isolation model for agents.
Create an inbox in one request
Signup-lite: no password. You get a hashed API key and research-bot@cooperemail.com.
POST
/api/v1/keyspublicSignup-lite: issue a hashed API key. With Bearer, adds another key.
{ "name": "agent-prod" }POST
/api/v1/inboxesBearerCreate username@cooperemail.com.
{ "username": "support", "display_name": "Support" }GET
/api/v1/inboxesBearerList inboxes for the key.
POST
/api/v1/inboxes/:id/messagesBearerSend Internet mail via Cloudflare Email Sending, falling through to Resend on Cloudflare auth/permission errors, from username@cooperemail.com. Accepts text, html, and attachments [{filename, content_type, content_base64, content_id?}]. Inline images use content_id and cid: in HTML. If no sending credential is usable, the API returns smtp_not_configured — Cooper does not fake a send.
{ "to": ["ada@example.com"], "subject": "Hello", "text": "Tuesday works.", "html": "<p>Tuesday works.</p><img src=\"cid:logo\" alt=\"\" />", "attachments": [{ "filename": "logo.png", "content_type": "image/png", "content_base64": "iVBORw0KGgo…", "content_id": "logo" }], "client_id": "send-001" }GET
/api/v1/inboxes/:id/messagesBearerList messages, newest first. :id can be inbox id, username, or email.
GET
/api/v1/inboxes/:id/messages/:msgIdBearerGet one message. Prefer extracted_text over text.
POST
/api/v1/inboxes/:id/inboundBearerAgent test injector (Bearer). Production inbound is POST /api/v1/internal/inbound from the Cloudflare Email Worker (X-Cooper-Inbound-Secret).
{ "from": "Ada <ada@example.com>", "subject": "Re: Hello", "text": "Confirmed.\n\nOn Tue, bot wrote:\n> Tuesday works." }GET
/api/v1/search?q=BearerFull-text search across stored mail for the account. Today: subject, extracted_text, addresses. Next: attachment text + historical backfill.
POST
/api/v1/webhooksBearerRegister a URL for message.received / message.sent.
{ "url": "https://example.com/hooks/cooper", "events": ["message.received"] }