Hee hee, how about one called "Allow me to save MYSELF some time"?
Dear Sheilah,
It was a genuine delight meeting you at the Wallsingharrowbrookhavenburyshire Writers Conference! I have followed your work avidly and I am very enthusiastic about the "Message to Writers" you posted at your website. I took to heart the advice you gave me at the Conference and re-worked my novel, A Touch of Kindness. I feel it is now ready for the market.
After careful consideration, I have decided not to offer it to you for representation.
Best,
Cathy S