Advertise on the exterior of your mail – do not make your customers guess what you do! Include on the exterior of your envelope your full address, #800 phone number, your company website address, small bullet points featuring your major products, specials you have going today, 2 for 1 sales, free shipping events, extended warranties for all sales this month, etc. The recipient of your letter should be able quickly to see what your firm sells. (i.e. “Websites that sell”, “affordable modern furniture”, “mufflers for every auto/truck”, “great donuts and donut holes”, “beautiful landscaping plants”. If you want something temporary, run labels with the specials and change them out every few weeks. Make the reader looking at your envelope know before opening it what you are selling. Never make them guess because you look suspicious or ashamed.