Quickstart

This takes you from a new account to an email delivered through the API. Allow about fifteen minutes; most of it is waiting for DNS.

Create a workspace.
Add your domain and an address on it.
Create an API key.
Send an email.

Create a workspace
Sign up at app.koltrix.com and name your workspace. You are its owner; invite teammates later from Settings → Team.
New workspaces start on a trial with tighter limits. They are listed under Limits and quotas.

Add your domain and an address

Open Settings → Domains & addresses and click Add domain. Enter the domain you want to send from, such as acme.com. Koltrix shows five DNS records to add at your DNS provider, each with a copy button:

Record	Name	What it does
Ownership (TXT)	`_koltrix`	Proves you control the domain.
MX	`@`	Delivers your domain's mail, including replies, to Koltrix.
SPF (TXT)	`@`	Lets Koltrix send for the domain. If you already have an SPF record, Koltrix shows a merged one to replace it with.
DKIM (TXT)	`kx1._domainkey`	Signs your mail so it can't be forged.
DMARC (TXT)	`_dmarc`	Tells receivers what to do with forgeries.

Custom domains and DNS explains each record, with notes for Cloudflare, GoDaddy, Namecheap and Route 53.

Click Check again after you have saved them. DNS usually takes a few minutes and sometimes a few hours. The domain becomes verified when all five records check out.

Then click Add address on the domain and add the mailbox you will send from, such as [email protected]. The API only sends from addresses added this way; any other From address is refused, even on a verified domain.

Create an API key
Open Settings → API keys and click Create key. Name it (for example "Local development") and keep the default scopes, read and send.
The key starts with kx_ and is shown once. Copy it now:
```
export KOLTRIX_KEY="kx_..."
```
Check it works:
```
curl https://api.koltrix.com/api/v2/me -H "Authorization: Bearer $KOLTRIX_KEY"
```

Send an email

curl https://api.koltrix.com/api/v2/emails \
  -H "Authorization: Bearer $KOLTRIX_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: quickstart-1" \
  -d '{
    "from": "[email protected]",
    "to": ["[email protected]"],
    "subject": "Hello from Koltrix",
    "body_html": "<h1>It works</h1><p>Sent with the Koltrix API.</p>"
  }'

Koltrix answers 202 Accepted:

{
  "id": "6f1c2a9e-3b7d-4e41-9a52-0c8d1f3e7b20",
  "status": "queued",
  "queued": true,
  "tracking_url": "/api/v2/messages/6f1c2a9e-3b7d-4e41-9a52-0c8d1f3e7b20",
  "recipient_count": 1
}

The email arrives a few seconds later. A copy is in your Koltrix Sent folder, and reply to it from your personal inbox to see the reply arrive in Koltrix.

Check its status:

curl https://api.koltrix.com/api/v2/messages/6f1c2a9e-3b7d-4e41-9a52-0c8d1f3e7b20 \
  -H "Authorization: Bearer $KOLTRIX_KEY"

status moves from queued to sent, and open_count goes up when you open it. (A 404 in the first second means it is still queued; try again.)

The same request in Node, Python, Go and PHP is in Sending email.

If it didn't arrive

What you see	What to do
`403` "from address … is not registered"	Add that exact address to the domain (step 2). The message says whether the domain itself is verified yet.
`401`	The key is wrong or revoked. Check you copied all of it, including `kx_`.
`status` is `bounced`	The `error` field has the receiving server's reason. A typo in the address is the usual cause.
`status` is `sent` but nothing arrived	Look in your spam folder, then check the domain's records in Settings: an unverified DKIM record is the usual cause.

Quickstart

Create a workspace

Add your domain and an address

Create an API key

Send an email

If it didn't arrive#

Next#

If it didn't arrive

Next