Total scam. Lawyers (especially in the US-not sure about Germany) don't usually write letters asking for money. First you would get a notice from a lawyer to cease and desist, and that legal action was going to be taken. Then a judge would have to order you to pay or not. A lawyer just isn't going to write a letter and say "I need a $1000 because you broke the law." Not going to happen I don't think. Smells like a scam to me.