I would like to confirm that you have received your appointment letter, here is a sample template you can use to write an acknowledgment letter for receiving an appointment letter.
To [Recipient name]
Dear, [Recipient name]
This letter is to acknowledge that I have received an appointment letter and would like to confirm my acceptance of the same. This was received on [Date] for the purpose of [Reason].
I am extremely elated to take part in [Event] thereby making a positive change to the best of my ability. I would like to thank you for this wonderful opportunity as it will help me acquire new skills.
I have signed and validated the appointment letter as instructed. Thanking you for your support and confidence.