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.
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The 3 Things To Avoid When Emailing Your List
When you decide to have an opt-in list, it is not just a matter of sending your subscribers your promotional newsletters or catalogs.