also known as transactive email. A creative format where the recipient can enter a transaction in the body of the email itself without clicking to a web page first. Transactions may be answering a survey, or purchasing something.

3 Quick And Easy Ways To Build A Profitable Opt-In List
You finally realize that you need a good opt-in list. After reading countless articles and sought expert advices and have read many success stories of people creating a small fortune with opt-in lists you finally decide to have one of your own.