Derek Harding has an article over at ClickZ, discussing the importance of letting subscribers go.
Many marketers are embracing the concept of a list exit strategy. That is, developing and managing a process to identify and gracefully remove recipients for whom a list is no longer valuable. Many lists have a long tail of recipients who have been on the list for a very long time but who also have not responded for a very long time. Apart from unconfirmed new registrants, these recipients are the most likely to bounce, complain, or to contain spam traps. Just as confirmation should be used at the beginning of list membership reconfirmation can be used at the end of the lifecycle to separate those recipients who wish to remain from those who have passed their “best before date.”
This is a really important part of list hygiene and one that many senders are just now starting to understand how important. Failure to keep recipients active and engaged does negatively affect delivery at some large ISPs now. As filtering knowledge and measurements filter down from the big ISPs, I expect more and more receiver domains to adopt similar filtering schemes.
Derek provides specific examples of how to use engagement, including triggers. When I have worked with customers on engagement campaigns, determining the right triggers is one of the challenges. The more data a sender has about customers, the more selective the sender can be about selecting triggers. Finding the right triggers and the right way to engage with subscribers is vital.