At a high level, it’s when a package has been physically accepted by the USPS clerks but hasn’t arrived at the sorting facility. This is when the shipper/sender receives the “shipment received package acceptance pending” notification.
Stages Leading to the Package Acceptance Pending Notification:
Postmasters physically accept your package or shipment of packages and the information is put into the USPS system.
This activates USPS tracking and the sender receives the “Shipment Received, Package Acceptance Pending” notification first.
USPS receives a large batch of shipments consisting of smaller units from the seller. While the large shipment gets scanned in bulk, the individual items take time to get scanned. This is why senders get the “package acceptance pending” notification.
When the individual package gets scanned, the tracking status will change to “Accepted at USPS Origin Facility. This is when the package will move between the USPS sorting centers.
Shippers receive further updates once the shipment gets sorted. The sorting process decides the time and route of the shipment.
When the parcel reaches the processing and distribution center called “Sectional Center Facility”, the sender will receive a new tracking status.
There are around 195 sectional center facilities in the U.S. They serve as a processing and distribution center for Post Offices in certain geographic areas which are defined by the first three digits of the zip codes in those offices.