Promotional material sent to existing or potential customers (at home or at work) through the post. It might be used initially to inform prospective customers of a business’s products / services and, on an on-going basis, to keep these customers, once secured, informed of product developments, in order to build customer loyalty. It requires the use of mailing lists, either obtained from a business’s database of past and present customers, or purchased from external sources. The promotional material sent to customers may be in the form of letters, newsletters, catalogues, brochures, booklets and price lists, and may include free samples or coupons.