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Koltrix docs

Quickstart

Send your first email from the API in three steps.

1. Create an API key

Sign in at app.koltrix.com and head to Settings → API Keys. Click New key, give it a name (e.g. “Local dev”), and copy the kx_… secret that appears. We only show it once.

2. Add a sending domain

Settings → Domains → add your domain. Set the MX, SPF, DKIM, and DMARC records shown on the verification page. Once they all turn green you can send from any address on that domain.

While the domain is new, Koltrix runs an automatic warm-up: 50 / day in week 1, 200 / day in week 2, ramping up to unlimited by week 9. You can see the live state under Settings → Warmup.

3. Send a transactional email

curl https://api.koltrix.com/api/v2/emails \
  -H "Authorization: Bearer kx_..." \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $(uuidgen)" \
  -d '{
    "from": "[email protected]",
    "to": ["[email protected]"],
    "subject": "Hello from Koltrix",
    "body_html": "<h1>Hi</h1><p>It works.</p>",
    "body_text": "Hi\n\nIt works."
  }'

Response:

{ "queued": true, "id": "email:send" }

That's it — the worker takes it from there. Visit Settings → Email logs to see delivery status, opens, clicks, and bounces.

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