Dear prospective employer:
Thank you for taking the time to send me a rejection letter. However, as you can imagine, I receive far more rejection letters than I am able to accommodate.
Though your rejection is quite impressive, I have received a wide pool of potential rejections, and was able to find some that better meet my needs.
Therefore, I regret to inform you that I am not able to accept your rejection, and will commence my employment at your establishment in two weeks.
I wish you the best of luck in your future potential hire rejection plans.