Ebay Standard Envelope used for fast shipping:

Tracking updates are received when the QR code is scanned by a sorting machine within a terminal. It is not uncommon for envelopes to miss their scan for an update or be marked as delivered when the envelope has not been physically received yet. If an envelope is scanned within radius of its destination, the tracking update will show delivered. Please allow an additional 1-3 business days for delivery if you receive a delivered status without physically receiving the envelope. All cards delivered within a plastic sleeve for protection.