Yankee slugger Mark Teixeira got a round of World Series blessings from residents of Greenwich, Conn., while dining at Rebecca’s on Tuesday night. The first baseman, who was eating with former Sony Music Label Group chairman Donnie Ienner, was repeatedly asked to sign autographs and toasted by diners throughout the meal. “He was extremely gracious,” says a spy. “And very focused.” Ienner used to work closely with Mariah Carey — the ex of Teixeira’s teammate Derek Jeter.