The Postal Service seems to be having a mold problem. In 2011, it closed the post office in Royalton, Kentucky, because mold had rendered it unsafe. Last year, post offices in Knox, New York, and Bangor, Wisconsin, were deemed unsafe and unsanitary for customers and employees because of mold and other problems. This week, the post office in Dupree, South Dakota, was closed because of mold that developed after some water got into the building. Read more.