The process of removing identical entries from two or more data sets such as mailing lists. AKA merge/purge. Delivered email: Number of emails sent minus the number of bounces and filtered messages. A highly inexact number because not all receiving ISPs report accurately on which email didn’t go through and why not.
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.