{
    "$schema": "http://json-schema.org/draft-04/schema#",
    "additionalProperties": false,
    "properties": {
        "customer": {
            "type": "string"
        },
        "message": {
            "type": "string"
        },
        "recipients": {
            "items": {
                "type": "string"
            },
            "type": "array"
        },
        "sender": {
            "type": "string"
        }
    },
    "required": [
        "customer",
        "message",
        "recipients"
    ],
    "type": "object"
}