Newsletters are regular - weekly or monthly - news letters sent by e-mail to subscribers or to a closed user group. They can be company information sent to employees, information newsletters in which new products, business news or information
about new techniques, processes or concepts are published like in a newspaper. Hypertext Markup Language (HTML) or Portable Document Format (PDF) are often used as file formats
fore-mail newsletters. E-mail newsletters may only be sent to interested parties, customers or employees if they have given their consent to receive the newsletter by means of a double opt-in
. In addition to the normal newsletter, there is also the enhanced newsletter.
With this concept, the newsletters are created jointly by several companies and emailed to the interested parties. Such an enhanced newsletter contains information from different companies, which, if possible, have a similar information offer or where the products complement each other.