curl -u [ username:password ] -X POST "https://opensearch-api.domain.tld/_plugins/_notifications/configs" \
  -H "Content-Type: application/json" -d '{
  "config_id": "postfix-email",
  "name": "postfix-email",
  "config": {
    "name": "postfix-email",
    "description": "Postfix relay for alerting",
    "config_type": "smtp_account",
    "smtp_account": {
      "host": "postfix",
      "port": 25,
      "method": "none",
      "from_address": "[email protected]"
    }
  }
}'
{"config_id":"postfix-email"}

curl -u [ username:password ] -X POST "https://opensearch-api.domain.tld/_plugins/_notifications/configs" \
  -H "Content-Type: application/json" -d '{
  "config_id": "ops-email-group",
  "name": "ops-email-group",
  "config": {
    "name": "ops-email-group",
    "config_type": "email_group",
    "email_group": {
      "recipient_list": [
        { "recipient": "[email protected]" }
      ]
    }
  }
}'
{"config_id":"ops-email-group"}