In the early 1980s I worked with my first oil and gas geologist. Randy's background was solid, but his attitude was negative. He was full of reasons why things wouldn't work.
Randy did put a lot of energy into writing a sales letter, and it came out very well. Then he put a lot of time and effort into collecting a list of names to mail that letter to. Surprisingly, after all that work, he never mailed his letters. I'm not sure why. Maybe he was afraid they wouldn't work.
Direct mail is an interesting business. You never know what the results will be until after you mail the letters. Guesses as to what will happen are often wrong. So don't second guess yourself. Mail your letters!