{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$id": "https://api.sparkpost.com/schemas/transmission",
  "title": "SparkPost Transmission",
  "description": "Schema for a SparkPost email transmission request",
  "type": "object",
  "properties": {
    "campaign_id": {
      "type": "string",
      "maxLength": 64,
      "description": "Campaign name for grouping transmissions"
    },
    "description": {
      "type": "string",
      "maxLength": 1024,
      "description": "Human-readable description of the transmission"
    },
    "metadata": {
      "type": "object",
      "additionalProperties": true,
      "description": "Transmission-level metadata passed to webhooks"
    },
    "substitution_data": {
      "type": "object",
      "additionalProperties": true,
      "description": "Template substitution data for all recipients"
    },
    "return_path": {
      "type": "string",
      "description": "Envelope FROM address for bounce handling"
    },
    "options": {
      "type": "object",
      "properties": {
        "start_time": {
          "type": "string",
          "format": "date-time",
          "description": "Schedule transmission for future delivery (max 3 days ahead)"
        },
        "open_tracking": {
          "type": "boolean",
          "description": "Enable open tracking pixel"
        },
        "click_tracking": {
          "type": "boolean",
          "description": "Enable click-through tracking"
        },
        "transactional": {
          "type": "boolean",
          "description": "Classify as transactional email"
        },
        "sandbox": {
          "type": "boolean",
          "description": "Use sandbox mode for testing without sending"
        },
        "skip_suppression": {
          "type": "boolean",
          "description": "Bypass suppression list check"
        },
        "ip_pool": {
          "type": "string",
          "description": "IP pool ID to use for sending"
        },
        "inline_css": {
          "type": "boolean",
          "description": "Inline CSS styles before sending"
        },
        "perform_substitutions": {
          "type": "boolean",
          "description": "Whether to perform substitution data replacement"
        }
      }
    },
    "recipients": {
      "oneOf": [
        {
          "type": "array",
          "items": {
            "$ref": "#/definitions/Recipient"
          },
          "description": "Inline recipient list"
        },
        {
          "type": "object",
          "required": ["list_id"],
          "properties": {
            "list_id": {
              "type": "string",
              "description": "ID of a stored recipient list"
            }
          }
        }
      ]
    },
    "content": {
      "$ref": "#/definitions/Content"
    }
  },
  "required": ["recipients", "content"],
  "definitions": {
    "Recipient": {
      "type": "object",
      "required": ["address"],
      "properties": {
        "address": {
          "oneOf": [
            {
              "type": "string",
              "format": "email"
            },
            {
              "type": "object",
              "required": ["email"],
              "properties": {
                "email": {
                  "type": "string",
                  "format": "email"
                },
                "name": {
                  "type": "string"
                },
                "header_to": {
                  "type": "string"
                }
              }
            }
          ]
        },
        "tags": {
          "type": "array",
          "items": {
            "type": "string"
          },
          "maxItems": 10
        },
        "metadata": {
          "type": "object",
          "additionalProperties": true
        },
        "substitution_data": {
          "type": "object",
          "additionalProperties": true
        }
      }
    },
    "Content": {
      "type": "object",
      "oneOf": [
        {
          "required": ["from", "subject"],
          "properties": {
            "from": {
              "oneOf": [
                { "type": "string" },
                {
                  "type": "object",
                  "properties": {
                    "email": { "type": "string", "format": "email" },
                    "name": { "type": "string" }
                  }
                }
              ]
            },
            "subject": { "type": "string" },
            "html": { "type": "string" },
            "text": { "type": "string" },
            "amp_html": { "type": "string" },
            "reply_to": { "type": "string" },
            "headers": {
              "type": "object",
              "additionalProperties": { "type": "string" }
            }
          }
        },
        {
          "required": ["template_id"],
          "properties": {
            "template_id": {
              "type": "string",
              "description": "ID of stored template"
            }
          }
        },
        {
          "required": ["ab_test_id"],
          "properties": {
            "ab_test_id": {
              "type": "string",
              "description": "ID of A/B test"
            }
          }
        },
        {
          "required": ["email_rfc822"],
          "properties": {
            "email_rfc822": {
              "type": "string",
              "description": "Raw RFC822 formatted email"
            }
          }
        }
      ]
    }
  }
}