{
    "expiration": "2100-01-01T12:00:00.000Z",
    "conditions": [
        {"acl": "public-read" },
        {"bucket": "sendgrid-open-source" },
        ["starts-with", "$key", "smtpapi-php/"],
        ["content-length-range", 2048, 268435456],
        ["eq", "$Content-Type", "application/zip"]
    ]
}