When you are testing to improve the performance of your direct mail letter, there are four essential parts of the letter to test: the headline (or Johnson box), the opening paragraph, the P.S., and subheads. These are based on how people scan and read letters.
If you do not grab your reader with these four elements, you don’t stand much chance of getting anything else read. Each of these elements has a purpose. In fact, your customer/prospect should be able to "get" your offer and your most important benefits after reading these four elements. The body copy in the letter should expand on each of the benefits promised in the head, subheads, P.S. and the first two sentences.
