A list developed by anyone receiving email, or processing email on its way to the recipient, or interested third-parties, that includes domains or IP addresses of any emailers suspected of sending spam. Many companies use blacklists to reject inbound email, either at the server level or before it reaches the recipient’s in-box. Also Blocklist and Blackhole list.

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.

