Only days after it was introduced, a proposed Senate overhaul of the U.S. Postal Service is taking its lumps from both organized labor and the mailing industry. “This bill is fatally flawed,” Cliff Guffey, president of the American Postal Workers Union, said in a Friday statement denouncing the legislation as a betrayal of USPS employees. The Association for Postal Commerce, which represents business mail users, has some “significant issues” with the measure, such as its idea for widening the Postal Service’s discretion in applying an inflation-adjusted cap on rate increases for standard mail and other areas where it dominates the…