A processing system and method for nationwide commingling of mail items to increase efficiency and lower mailing costs includes a pre-sort facility which creates a first set of diverted mail items and a first set of associated data while a print and mail manufacture facility generates a second set of manufactured mail items and a second set of associated data and then receives the first set of diverted mail items and first set of associated data from the pre-sort facility and then commingles the first and second sets of mail items according to a predetermined set of commingling rules applied to the first and second sets of associated data to produce commingled mail items which reduces postal costs in mailing the commingled mail item.