No, no it's not. We have evidence (in other words, IPs that they acquired through slightly questionable methods that they traced back to you through questionable methods) that you are infringing copyright. We will make this problem go away if you give us $2000. That's extortion, if you know the person doesn't have the resources to fight you in court and you sue them for a ridiculous amount of money. Based on very flimsy evidence.

I am the Doctor, and THIS... is my SPOON!