The process of measuring delivery rates by format, ISP or other factors and delivery failures (bounces, invalid address, server and other errors). An inexact science.
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.