It has informed by you that a mail received from one of ex-employee where in the fellow requested to issue No Objection Certificate.
The person could have been charged for the use of company's letterhead but he has not done anything. The person has shown his ignorance by providing the matter in a sheet that look alike your company's letterhead. The same behaviour can not be called the misuse or unauthorised use of company's letterhead for personal & vested interest.
When you are sure that nothing kind of misuse has happend, the matter ends there itself. As a bonafide employer you can issue him NOC and cautioned him for not to do or to return if any stationary is with him before issue.
The person could have been charged for the use of company's letterhead but he has not done anything. The person has shown his ignorance by providing the matter in a sheet that look alike your company's letterhead. The same behaviour can not be called the misuse or unauthorised use of company's letterhead for personal & vested interest.
When you are sure that nothing kind of misuse has happend, the matter ends there itself. As a bonafide employer you can issue him NOC and cautioned him for not to do or to return if any stationary is with him before issue.