The U.S. Postal Service is

The U.S. Postal Service is in fact working on an “e-post office box,” as I suggested last month. This article has few details about the proposed service (the explanation of how it will work is a little confused and the article doesn’t say when it will be available) but it does indicate the service will target businesses as well as consumers, and will include bill presentment and payment features.
Postal Service delivers online