The Direct Marketing Association is disputing the U.S. Postal Service's planned 6.4% postal rate hike. The DMA and members including American Business Media, Dow Jones & Co. Inc. and The McGraw-Hill Cos. are testifying before the Washington-based Postal Rate Commission. The USPS wants to increase rates by $3.4 billion; the DMA and its members want that amount limited to $1.8 billion. The postal rate hike is due to take effect next year.