After accusing Amazon of conducting a campaign to poach its third-party sellers, eBay has filed a lawsuit in California to ban the competitor from misusing its platform, per The Wall Street Journal. eBay first sent a cease and desist letter to Amazon earlier this month claiming its employees were using eBay’s messaging feature to try to hire away third-party sellers for Amazon Marketplace, the e-commerce giant’s competing sellers platform.

At the time, Amazon said it was “conducting a thorough investigation of these allegations.” Now, according to the WSJ, eBay is suing Amazon in Santa Clara county with the intent of banning its employees from ever misusing eBay’s messaging platform. eBay is also seeking unspecified damages as monetary relief for the lost sales. Both Amazon and eBay take commission on sales sold using its platform, while Amazon in particular makes a good deal of money providing stocking, shipping, and other packaging logistics support to these sellers.

eBay is accusing Amazon of running a “systematic” poaching effort

According to eBay’s complaint, Amazon orchestrated this poaching effort from its headquarters, with standardized messages that were similar or in some cases identical and being sent from Amazon representatives in the US, parts of Europe, Singapore, and Australia. According to eBay’s terms of service, you cannot use its messaging system to conduct or promote outside businesses or spam other buyers and sellers. Yet Amazon reps were sending sometimes as many as 120 messages with a single eBay account without buying or selling any items on the site.

“For years, and unbeknownst to eBay, Amazon has been engaged in a systematic, coordinated effort to infiltrate and exploit eBay’s proprietary M2M system on eBay’s platform to lure top eBay sellers to Amazon,” eBay writes in its complaint. “The scheme is startling in breadth — involving large numbers of Amazon representatives targeting many hundreds of eBay sellers, and spanning several countries overseas and many states in the United States (including California).”

Though it may seem to those unfamiliar with eBay and Amazon’s business models that the two sites serve largely different customers, they have over the years begun to overlap. Amazon has diversified its retail operation to include third-party sellers that can sell products direct to consumers, while eBay has grown from an auction site for used goods to a place where companies can create entire e-commerce operations. It’s now clear the two are in direct competition, at least for online marketplace sellers who may use only one of the two platforms to conduct business. Amazon declined to comment for this story.