The policy of not issuing appointment letter is petty and it actually serves no purpose. Yes, there will be no records regarding appointment but then the appointment can be proved by other circumstantial evidence and there would be plenty of them. Like a copy of attendance registers or even e-means used, the record of instructions received, use of official means of communication etc etc. So it does not really help. Now that it is proposed to issue it, the best option is to appoint from the original date itself, but have a proper designation, pay and other terms and conditions including the period of probation, notice period etc. An employee has to feel wanted in his workplace, issuing an appointment order confirms that feeling.