A newsletter is a printed report containing news (information) of the activities of a business (legal name; subscription business model) or an organization (institutions, societies, associations) that is sent by mail regularly to all its members, customers, employees or people, who are interested in. Newsletters generally contain one main topic of interest to its recipients. A newsletter may be considered grey literature. E-newsletters are delivered electronically via e-mail and can be viewed as spamming if sent unsolicited.[1]