Direct mail sales letters are an effective way of presenting products, according to respondents to the 2010 B2B Marketing Benchmark Report by research firm Marketing Sherpa. The report notes that the ability to personalize and segment the content of sales letters makes them a cost-effective way of communicating directly with a target audience, compared with media such as advertising.

Personalize the Letter

Where possible, address the recipient by name. Throughout the letter, use the person’s name or the word “you,” rather than an impersonal term like “customers” or “engineers.” Personalization helps to build a relationship with prospects or customers by demonstrating that you are interested in meeting their unique needs, according to Entrepreneur.

Write a Strong Headline

The headline must give the recipient a good reason to continue reading. It should offer a benefit that is relevant and important and show how the product will meet the reader’s needs. The “how to” type of headline gives you the opportunity to demonstrate powerful benefits. A letter presenting a financial product to seniors might open with a headline such as “How to avoid running out of money when you retire.” A sales training firm might address sales managers with a headline such as “How to improve the productivity of your sales team by 20 percent.”

Build Rapport by Addressing Needs

Instead of telling readers you have a great product, explain how you understand their needs and challenges. If you have contacted the letter's recipients previously, refer to discussions on their requirements. Alternatively, refer to independent research that is relevant to readers’ needs and explain why your product offers a solution to their challenges. An example might be: “A recent study shows that sales force productivity has fallen over the last two years.”

Describe the Product’s Benefits

Describing benefits lets readers know what they will gain by using the product, rather than simply listing features that may not be relevant or interesting, according to Changing Minds. Where possible, include figures to show the scale of the potential benefits -- for example, “You will reduce production line waste 15 percent by using this quality management system.”

Include Your Credentials

If you are writing to prospects who may not know your company, include information explaining why you have the expertise and experience to solve their problems with your product. Using names of satisfied customers or testimonials adds further credibility to your pitch, according to Oracle.

Finish With a Call to Action

The introductory letter is the first stage in a process that leads to a sale. To encourage prospects to take the next step, finish the letter with a call to action. You might ask them to visit a website for more information, or tell them that you will call to arrange a demonstration or a meeting with a sales representative. Including an offer such as a discount for orders placed within seven days can stimulate response.