NatureBox does not require a signature for delivery. Generally your postal carrier will leave your shipment in a secure location if you are not home at the time of your delivery. If the postal carrier feels there is no secure location available, they may redeliver the next business day or they will take your box back to your local post office.
If you missed your delivery and you were unable to locate your box on premise, check your tracking information for information on the status of the box. If the tracking states "Notice Left" but there is no notice, you can schedule a redelivery by following the steps here.