The best thing to do is to know that law and your legal rights. Anybody can write a cease and desist. It is a first step towards a lawsuit, but given how inexpensive they are to write they are an easy way to intimidate small businesses.
Looking back, these companies can send these things out for no cost, looking for you to mess up by replying. If they want to sue you, don't worry, it will happen.
As my attorney once opined: if they really want to sue you, the first thing you'll hear from them will be about the lawsuit they filed, not a C&D.
Usually the terms of service you sign up to make it clear which jurisdiction disputes would be adjudicated in
For me, as a UK citizen/resident it was Ireland. Which is great since I've never been there, but I've heard their courtrooms are lovely in the springtime
It is certainly true that anyone can respond to a C&D letter. But whether you can do so without doing more harm than good is another question.