When I was PMR at the post office eBayers were the worst.

First, the package is supposed to be mailed on the day you print the label.

Second, if you have multiple packages the shipper is supposed to print a manifest, The manifest is a list of all the printed labels with one bar code that's scanned instead of scanning each parcel individually.

I used to have a real pain in the ass customer who would understate the weights on the labels and hold all her packages for a week or two then come in with 80-120 at once with no manifest. I dispatched the parcels without scanning any the first two times she did this. When she came in to complain I made her wait while I checked the date on the labels and returned the ones that were out of date so she could take them back home and reprint the labels. I also told her to have the correct weights on the labels and have a manifest to scan the next time she was bringing more than a few packages.

The USPS is full of dips-hits on both side of the counter!