{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "CampaignRecipient",
  "type": "object",
  "properties": {
    "email": {
      "type": "string",
      "description": "Recipient email address."
    },
    "lead_id": {
      "type": "['integer', 'null']",
      "description": "Associated lead identifier."
    },
    "sending_status": {
      "type": "string",
      "description": "Current sending status for this recipient."
    }
  }
}