The USPS seeks an industry-proven, Software-as-a-Service (SaaS), commercial off-the-shelf (COTS) software solution to standardize, automate, and streamline the process for sourcing supplies, services, equipment, and facilities. The eSourcing solution will include the following applications: (1) Optimization (both self-service and full-service), (2) eRFx (including supplier portal), and (3) Reverse Auction (RA).