I went into the West Portal Post Office, the line was long, this is COVID-time, I am in a high risk-group, and I wanted to drop off the pre-paid labeled package without standing in the line to get a receipt. However, I was aggressively questioned by an employee, stating "you do not have enough postage, I know, that looks over 13 ounces"--I told her that my prepaid label was up to 1 pound, and she said I was wrong--13 ounces was the limit, and she threatened to send my package back to me. I left the package, because if it was one ounce over, USPS is supposed to deliver the package per Mercari policies, and charge me for any excess. However, this package was routed back to me, noting postage due of $2.35, which invalidated my prepaid label. And to complicate things further, Mercari still thinks the package was delivered to the buyer! This has caused a bit of a mess, and of course a delay, and I am not happy that I had to buy additional postage to send this package. I will be in contact with the supervisor of this local post office; however, the phone just rings and rings. Oh my. Lesson learned--do not go to this local post office!