Would it not need something written (paper) in the US to start anything? In most european countries you just ignore mails with stuff like this and wont be scared in anyway, just as you are not to be scammed by our beloved nigerian prince.
Not a lawyer, but: Not really. You do have to present the case to the judge in a certain format to start it, but as I understand it, there's no requirement for you to send notice to the guy you're suing in a specific format. Once the suit starts, contacting the other party is taken care of either by the court or by your lawyer.