A one-time broadcast to an email list, separate from regular newsletters or promotions, and often including a message from an outside advertiser or a special promotion from the list owner.

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.