put on notice
when an attorney sends you a letter, puts you on notice concerning a number of issues,and you don't agree that they have the right to enforce such issues,are you required to answer or even acknoweldge the letter? By not answering ,are you implying that you agree with the issues included in the notice?
Re: put on notice
Generally the answer to your question is "no". If you are wrong, however, you may end up paying the consequence of ignoring the notice. One example is if you recieve a notice of pending litigation and to retain all electronic data and emails regarding a certain issue. If you ignore the notice and are wrong, then the court may consider your actions to be spoliation of evidence which would hurt you in a trial.
It would be wisest to invest in preventive "medicine" here by going to an attorney with the letter and get advise on it.