@ Kamlesh,
It is felt that you may show the NDA, appointment letter, employee rule book, service rule book, HR policy to a competent and experienced labor consultant/service lawyer having expertise in such matters and seek expert advice. Let your lawyer examine each detail and arrange to issue fitting reply to the legal notice.
The attached article is informative.
Conclusion-
Negative covenant which restricts the employee beyond the period of employment are considered to be unreasonable. The exception being extended to confidential information and non-solicitation agreement to a reasonable period of time are valid and clauses like "garden leave" does not seem to protect the employer when it comes to Court of law; as they are considered to be agreement in restraint of trade and does not serve the purpose for which it was intended. Therefore, it requires the mind of an artist to draft a negative clause and the foresight of a prophet to view the consequences of such a clause which has now become absolutely imperative considering the decisions made by the India Courts.
You may go they the attachment:
Polaris Software Lab. Limited ... vs Suren Khiwadkar on 8 September, 2003
3. In all these applications, we are concerned with the common points:
Is the covenant embodied in the Appointment and Undertaking can be enforced during the post service period and after the termination of services of the defendants:
Since this common point for determination arises in all the. applications, all the applications were heard together and disposed of by this Common Order.
“In my view, the relief sought for by the plaintiff Company is obscure and unclear. What is the nature of information which the defendants have gained and what part of information that the defendants are attempting to divulge is unclear. The confidentiality and the information which a person has gained in his mind is purely subjective and cannot be decided by the objective assessment.”
19. The Agreement of Undertaking and the confidential Agreement, Non-disclosure Agreement is valid and could survive only during the subsistence of the contract and course of employment; The distinction between the restraints imposed by a contract operative during the subsistence of the contract of employment and those operative after the termination of service is of fundamental character. The purpose, incidents and consequences of the two types of restraints need to be borne in mind before proceeding to consider the submissions made by the counsel for the plaintiff who seeks for a restraint as claimed in the applications.
Thus the judgment of the Supreme Court is emphatic in its conclusion, that in India, the restraints are operative only during the subsistence of the contract and the restraints could be valid only during the period of contract.
https://www.lawyersclubindia.com/articles/Non-Compete-Clauses-and-The-Indian-Contract-Act-1972-4621.asp
The article at the above link at LCI by Apurva Thakur is very informative and contains reference of lots of court judgements.
Yu may go thru the attachment:
Bombay High Court
Vfs Global Services Private ... vs Mr. Suprit Roy on 10 December, 2007
The legal position was summarised as follows:
The legal position with regard to post-contractual covenants or restrictions has been consistent, unchanging and completely settled in our country. The legal position clearly crystallised in our country is that while construing the provisions of Section 27 of the Contract Act, neither the test of reasonableness nor the principle of restrain being partial is applicable, unless it falls within express exception engrafted in Section 27.
the prayer therein which seeks an injunction from soliciting customers and employees and from interacting with UK Visas or from using any contact made by the Defendant with embassies and consulates cannot be granted. The relief as claimed is vague and shall accordingly stand refused. The Defendant has agreed to complete all formalities for handover of duties.