Credit: Ryan Plummer/Crown Media LLC Signed, Sealed, Delivered In October 2013, fans were introduced to the Postables a.k.a the Dead Letter Office workers for the U.S. Postal System. Oliver O’Toole (Eric Mabius) leads his team of oddball characters — including Rita Haywith (Yan-Kay Crystal Lowe), Norman Dorman (Geoff Gustafson) and Shane McInerny (Kristin Booth) —…