I have studied Chinese for several years, but I have never learned the proper way to write letters in Mandarin, especially when it comes to salutations. Are there idioms like "Sincerely," "Best," or "Yours truly," that are used in China to close a letter? I am writing to a much older woman, and if it matters, I do not know her particularly well.
Forgot to mention–the tone is most like a thank-you letter, I suppose.