Luis Castillo, Paul Lo Duca, Marlon Anderson, Ramon Castro, Damion Easley and Shawn Green filed on Monday, the first day of the filing period.
Tom Glavine, Moises Alou, Jose Valentin, Brian Lawrence and Jeff Conine are the only other members of the 2007 Mets eligible for free agency. The filing period ends on Nov. 12.
Sele said he wouldn't return to the Mets, and Alomar was likely to retire. If DiFelice were to re-sign with the club, he probably would serve as a Minor League catcher and unofficial coach, the same roles that he filled most of last season.
Glavine, who chose not to exercise his option for a contract with the Mets for 2008, hasn't yet determined whether he will pitch next season.
Marty Noble is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.