curl --request GET \
  --url https://api.railmail.app/api/v1/sending-domain/dns-instructions \
  --header 'X-API-Key: <api-key>'

{
  "domainName": "<string>",
  "requiredRecords": [
    {
      "id": 123,
      "recordType": "<string>",
      "host": "<string>",
      "expectedValue": "<string>",
      "actualValue": "<string>",
      "status": "<string>",
      "lastCheckedAt": "2023-11-07T05:31:56Z",
      "failureReason": "<string>"
    }
  ],
  "instructionsText": "<string>"
}