json_schema: {
      "additionalProperties": true,
      "description": "Schema for a Mailgun message delivered event",
      "properties": {
          "domain": {
              "_format": "hostname",
              "description": "Domain that sent the original message.",
              "maxLength": 256,
              "type": "string"
          },
          "event": {
              "description": "Event name ('delivered').",
              "maxLength": 16,
              "type": "string"
          },
          "messageHeaders": {
              "description": "String list of all MIME headers of the original message dumped to a JSON string (order of headers preserved).",
              "type": "string"
          },
          "messageId": {
              "description": "The Id of the message that delivered.",
              "maxLength": 1024,
              "type": "string"
          },
          "recipient": {
              "_format": "email",
              "description": "Intended recipient.",
              "maxLength": 256,
              "type": "string"
          },
          "signature": {
              "description": "String with hexadecimal digits generate by HMAC algorithm (see securing webhooks).",
              "maxLength": 128,
              "type": "string"
          },
          "timestamp": {
              "_format": "date-time",
              "description": "Timestamp in ISO8601 format.",
              "type": "string"
          },
          "token": {
              "description": "Randomly generated string with length 50 (see securing webhooks).",
              "maxLength": 50,
              "minLength": 50,
              "type": "string"
          }
      },
      "self": {
          "format": "jsonschema",
          "name": "message_delivered",
          "vendor": "com.mailgun",
          "version": "1-0-0"
      },
      "type": "object"
  }