Jonathan Papelbon is shipping down to Philly.

And the Red Sox aren't about to stop him.

Papelbon has received a four-year contract offer from the Philadelphia Phillies that "seems like a done deal," a major league source told the Herald yesterday. The deal is expected to be worth $50 million, the richest ever for a reliever, eclipsing the $47 million (five years) Toronto gave to B.J. Ryan in 2005.

Pending a physical, which will happen early next week, Papelbon's run with the Red Sox will be over. The four-time All-Star converted 219 saves, posted a 2.33 ERA and, of course, recorded the last out of the 2007 World Series.