Dear friend,
Your first query was limited to the validity of the legal notice sent through email, and I had responded to it. However, in your second post, you have provided brief information about the reason for the legal notice. Nevertheless, without knowing the background of the case and the contents of the notice itself, it is not possible to offer any advice.
In light of this, your friend may consider seeking the assistance of a lawyer to obtain proper legal advice.
Thanks,
Dinesh Divekar