See this example for a good example of how to keep the quality of your email list high. The grim reality is that subscribers tend to interact with your newsletters less as time goes by. This begs the question, why would you want subscribers who signed up three, four, or five years ago on your list? There is a good chance these subscribers are just fluff and not driving much traffic to your site.
I received this excellent example from MediaPost. Instead of waiting until their list grows old and tired to clean it up, they keep their list evergreen by maintaining an annual subscription model. As you can see, my subscription is up this month and they recently started running these renewal reminders at the top of my daily email.
By doing this, MediaPost keeps their list fresh, response rates up, and keep themselves out of trouble often associated with mailing to old names (such as hitting dead inboxes that most ISPs monitor). Many fear that by adopting this approach, they will drastically cut into the size of their list. This is not completely unwarranted, but it is short-sighted. Despite the annual subscription approach (which by the way has worked for print subscriptions for years) MediaPost is able to keep the size of their list up. According to Mediapost's media kit, circulation for the EmailInsider newsletter is 58,000... pretty impressive for a high quality B2B email list.
