which is the most common use of opt-in e-mail marketing
Email marketing A common example of permission marketing is a newsletter sent to an advertising firm's customers. Such newsletters inform customers of upcoming events or promotions, or new products.[14] In this type of advertising, a company that wants to send a newsletter to their customers may ask them at the point of purchase if they would like to receive the newsletter.
Gallup (company) Gallup, Inc. is an American research-based, global performance-management consulting company. Founded by George Gallup in 1935, the company became known for its public opinion polls conducted worldwide. It provides research and strategic consulting to large organizations in many countries,[2] focusing on "analytics and advice to help leaders and organizations solve their most pressing problems".[3]