curl --request GET \
  --url https://staging.terminal3.io/v1/sub_client \
  --header 'x-api-token: <x-api-token>'

{
  "data": [
    {
      "client_id": 123,
      "name": "<string>",
      "domain": "<string>",
      "timezone": "<string>",
      "address_1": "<string>",
      "address_2": "<string>",
      "country": "<string>",
      "province": "<string>",
      "city": "<string>",
      "subdomain": "<string>",
      "from_email_address": "<string>",
      "esp_token": "<string>",
      "recaptcha_key": "<string>",
      "recaptcha_threshold": 123,
      "recaptcha_enabled": true,
      "created_at": "<string>",
      "privacy_link": "<string>"
    }
  ],
  "per_page": 123,
  "current_page": 123,
  "total_pages": 123
}