There are the book people, the jewelry people, the movie people, the electronics people. They greet each other with knowing nods as they inspect the goods inside a cavernous warehouse on the west side of Atlanta that is the end of the line for undeliverable mail. Once a month the United States Postal Service auctions off the valuable stuff it cannot deliver at Atlanta’s Mail Recovery Center. But at a time of rapid change for the Postal Service, last month’s live auction was one of the last. The Postal Service is contracting out the auctions and moving them all online as soon as April. GovDeals, the contractor, says expanding the pool of bidders beyond those who could show up in Atlanta will bring in more money for the cash-strapped Postal Service. The semi-private institution loses $25 million per day, according to Congressional testimony by Postmaster General Patrick Donahoe. Roger Gravley, the company’s vice president of client services and marketing, said GovDeals auctions have shown a 20 percent to 40 percent price increase over live auctions. A subsidiary of Liquidity Services Inc., GovDeals contracts with 5,300 governments to sell their surplus.