BAY SHORE - Some Bay Shore residents have launched a letter-writing campaign aimed at saving the town's historic post office that has been slated for closure. "We came up with this idea of 'Miracle on 34th Street,'" says Donna Periconi, of the Bay Shore Chamber of Commerce. "We will deliver 5,000 letters in the old white sacks just like they used in 'Miracle on 34th Street.'"A recent report in the Wall Street Journal found that the U.S. Postal Service is selling a growing number of historic buildings housing post offices to private businesspeople, who turn them into commercial establishments. However, Bay Shore residents say the historical significance of their post office is the exact reason why it should remain a post office."Downtown Bay Shore has really gone through a big revitalization with the hospital, the YMCA, the Boulton Center, and the post office is just as important to everybody in town," says Bob Pettersen, of the Bay Shore YMCA. Bay Shore residents will hold a rally in front of the post office next week when they deliver their letters.