There is a nationwide slowdown in the delivery scanning activity that we receive from the USPS. Historically, this does not mean your mail isn't being delivered, it means that the USPS isn't prioritizing the scanning of the barcodes during the holiday rush.
Backlogs in shipments are due to an overwhelming surge of e-commerce packages. Please see this article for more detailed information.
We would advise moving up your upcoming shipment to account for potential delays and ensure that your shipments arrive at the time you expect to receive them.