Maybe they haven’t sued the whole Internet, just a good chunk of it. Polaris IP, a patent firm, has filed a patent infringement suit against Google, Yahoo, Amazon.com, A9.com, Borders, AOL and IAC/InterActiveCorp, which owns Ask.com.

Polaris is the owner of United States Patent No. 6,411,947, for an “Automatic Message Interpretation and Routing System.” It is not entirely clear what the patent covers or how Google, Yahoo, et. al. infringed on it. We’ve contacted the lawyers for Polaris for details.

The patent appears to cover a customer service system that can analyze incoming customer e-mail messages and decide whether they can be handled automatically or need review by a human. According to the complaint, Polaris claims that Google’s advertising systems, including AdWords and AdSense, which analyze electronic messages to determine which ads to place next to them, infringes on its patent. Yahoo and others similarly infringe on the patent, according to the complaint.

Patent claims, of course, are a dime a dozen. And this case was filed in the United States District Court for the Eastern District of Texas, Marshall Division, the nation’s preferred venue for patent plaintiffs.

But last year Polaris filed a suit against Kana Software alleging that it had infringed the same patent. Kana settled the case in March and agreed to license the technology from Polaris, though terms of the settlement were not disclosed.