Product

The whole email stack for agents, one API.

ThreadCamp reconciles inboxes, sending and forwarding behind one key. Every primitive below maps to a real endpoint under /v1 - no glue code between three vendors.

Inboxes as a primitive

POST /v1/inboxes creates a real, addressable inbox on the shared relay.threadcamp.com domain; pass a verified custom domain for your own. Each inbox carries an autonomy policy and messages you can list by direction.

Resend-compatible sending

POST /v1/emails accepts the Resend payload shape - from, to, subject, text, html, cc - plus scheduled_at for delayed send and client_id for idempotency. Migrate by changing the base URL and key.

Forwarding Routes with SRS

POST /v1/routes defines a catch-all (*@domain) or alias Route that forwards to an off-platform address. SRS envelope rewriting and loop guards are applied automatically so SPF and DMARC survive the hop.

Custom domains, real verification

POST /v1/domains returns the DNS record set to place at your host. POST /v1/domains/:id/verify runs a real DKIM verification check - the domain stays pending until your records propagate, then flips to verified.

Human-in-the-loop approvals

The differentiator. Set an inbox to approve-first and any send from it is held as status pending_approval with an approval_id. A human resolves it via POST /v1/approvals/:id - approving is what executes the send.

Signed webhooks + event log

Webhooks are per-inbox: set callback_url on an inbox and inbound mail delivers an HMAC-signed email.received payload there (the signing secret is returned once at inbox creation). GET /v1/events is the inspectable activity log, derived from your message records.

New - nobody else ships this

Human-in-the-loop approvals

The category's biggest objection is blast radius: what if the agent emails the wrong person, at scale? Set an inbox to approve-first and every send from it lands as a pending draft. The send does not go out until a human calls POST /v1/approvals/:id with action "approve" - and that approval is what actually sends it. Reject instead, and the message is marked rejected and never leaves.

How approvals work

Agent-native surfaces

Built to be discovered and used unattended.

MCP server

A hosted and stdio (npx -y @threadcamp/mcp) MCP server exposes the API as callable tools - create_inbox, send_email, wait_for_message and more. See the MCP docs.

Machine-readable everything

llms.txt, /openapi.json and /pricing.json let an agent read the surface and self-select a plan.

Sandbox keys + idempotency

A public sandbox key (sk_test_sandbox_threadcamp_public_demo) lets agents try the API with no signup. client_id makes creates and sends safe to retry.

The three calls

Create an inbox, send, forward.

Create an inbox (approve-first)

curl https://www.threadcamp.com/v1/inboxes \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{ "display_name": "Support Agent", "autonomy": "approve-first" }'

# -> 201
# { "id": "inbox_...", "object": "inbox",
#   "address": "support-agent@relay.threadcamp.com",
#   "autonomy": "approve-first", "created_at": "..." }

Send an email (scheduled, idempotent)

curl https://www.threadcamp.com/v1/emails \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "from": "support-agent@relay.threadcamp.com",
    "to": ["customer@example.com"],
    "subject": "Your receipt",
    "text": "Thanks for your order.",
    "scheduled_at": "2026-08-01T09:00:00Z",
    "client_id": "receipt-8891"
  }'

# from an approve-first inbox -> 202
# { "id": "msg_...", "status": "pending_approval", "approval_id": "apr_..." }

Create a forwarding Route

curl https://www.threadcamp.com/v1/routes \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "match": "*@acme-agents.email",
    "action": "forward",
    "destination": "team@acme.com",
    "srs": true
  }'

# -> 201
# { "id": "route_...", "object": "route", "match": "*@acme-agents.email",
#   "action": "forward", "destination": "team@acme.com", "srs": true }

Give your agent the full stack in one call.

Inboxes, sending and forwarding on the free tier. No credit card.

Start free Read the docs