Which of these is NOT a reason a mail piece may be considered anonymous mail?

A mail piece is typically considered anonymous if it cannot be easily traced back to the sender. The characteristic that makes a piece anonymous includes various factors, such as the absence of a return address, which can prevent the recipient or postal service from identifying who sent it.

The fact that a mail piece weighs less than 13 oz does not inherently contribute to its anonymity. While certain weight classifications might affect service options or handling, they do not define whether a mail piece is anonymous. Therefore, a mail piece under this weight can still have a clear sender's identity through a return address or other identifying features.

In contrast, mailing options that include only postage stamps or submissions not accepted at a retail counter can add to the anonymous characteristics of a piece. The absence of a return address is a clear indication that the sender does not want to be identified, which directly relates to the anonymous nature of the mail.