Thank you very much for your recent rejection slip. As it does not quite fit my present requirements, I am returning it. This in no way reflects upon its merits.
Don’t be discouraged. I read your rejection slip with great interest, and I hope you’ll continue reading my work.
I appreciate your thinking of me and wish you the best of luck in placing your rejection slip elsewhere.
Just Another Writer
P.S. Please forgive me for the printed note. I’d like to comment on each rejection slip, but the large number I receive makes it impossible to answer each one personally.
[Disclosure: I wish I had written this. A friend passed it along to me.]