A customer newsletter service is the automation of a customer retention program in which a service host is responsible for designing, printing, and mailing the customer newsletter, although some variation to this method can be altered the main purpose is to provide a resource that a business might not have access to otherwise.
Customer newsletter services aim to provide newsletters at a cost lower than a business could, by already having formatted templates, as well as pre-defined newsletters that are designed to only be sent to one business per ZIP code (i.e., the first business to utilize will be the only one for that ZIP code).
References
Customer newsletter service Wikipedia(Text) CC BY-SA