An email service in which individual members post messages for all group members to read (“many to many.”) In contrast, a newsletter is a “one to many” broadcast, where comments by members or subscribers go only to the message sender. Aka by the trademarked name Listserv.

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.