What should you do if you receive a cease and desist letter claiming you are infringing someone else’s patent, trademark, domain name, or other intellectual property?
You want to address this situation strategically, and not ignore it. Get legal advice. Don’t respond on your own to the other side. There are a number of options available, including responding with a denial (but don’t this yourself – get an experienced IP attorney to write the response); not responding; doing what the letter demands (stopping the infringement or taking a license); or filing a declaratory judgment action asserting that the patent or trademark is invalid.