Optoro, the D.C.-area firm that helps big retailers re-sell extra inventory, said the venture capital arm of the United Parcel Service was part of a group that invested $30 million in the e-commerce company.

Optoro said UPS would partner with the company as part of the investment to open doors to new customer relationships.

UPS “has great relationships with the biggest retailers and brands,” said Optoro founder Tobin Moore. “We’re already targeting very large retailers but this allows us to implement relationships with large retailers faster.”

The latest funding round brings the total Optoro has received from investors above $100 million. It has already attracted capital from some of the region’s most prominent technology funders: Revolution Growth, the $1.1 billion venture firm backed by AOL co-founder Steve Case and Washington sports-teams owner Ted Leonsis, business executive Fred Schaufeld’s Swan & Legend Venture Partners, California private equity firm Kleiner Perkins Caufield & Byers, even Al Gore.

Optoro’s investors are betting on its ability to capitalize on what they say is a rapidly-growing cost for online retailers that offer liberal return policies at a time when shoppers expect free or low-cost shipping.

“That is a hidden, ticking time bomb” for retailers, Leonsis said in an interview. “If 15 percent of your stuff is coming back -- and you’re paying for it to come back — you better have really good automated solutions to help get the costs down.”

Returned goods often move through a network of middlemen that sort through the merchandise and buy what they think they can move, sometimes for pennies on the dollar. It’s a process that can eat away at retailers’ margins. Optoro’s solution is to use a set of complicated software algorithms to figure out, on a massive scale, where to send that excess inventory.

The company’s online brand Blinq allows customers to re-sell the goods to hundreds of millions of potential buyers. Moore boasts that his company has helped some big retailers double the “recovery rate” on returned items, such that they make up more of what they lose due to returned goods.

Leonsis says the partnership with UPS mainly lends Optoro the legitimacy it needs to work for the biggest retailers in the global economy, implying that its status as a young company is making it difficult to sign deals with established brands.

“The issue for Optoro is that if you’re a massive company and 10 percent of your sales is coming back in returns. . .are you going to trust a comprehensive solution of that size to such a young company?” he said. ”By partnering with UPS it helps to mitigate that risk to the company. It should help Optoro from a business standpoint grow faster.”

The company grew up in Lanham, Md. just outside the District’s city limits, but now runs most of its operations out of an office downtown. The funding round was reported by the Wall Street Journal Wednesday. Terms of the deal were not disclosed and Moore declined to discuss the company’s revenue or valuation, saying only “we’ve had a lot of great growth and expect to continue to grow.”