Content distributed to subscribers by email, on a regular schedule. Content is seen as valued editorial in and of itself rather than primarily a commercial message with a sales offer. See ezine.
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.