Here’s a tip for reinforcing the value of your newsletter and encouraging subscribers to open future issues:
In each issue, include a preview of the newsletter topic that follows. Not everyone plans their editorial calendar ahead, but if you do, it’s a great way to keep your subscribers looking forward to future issues.
You don’t necessarily have to promise that particular topics will appear in particular issues. If you don’t want to lock yourself in, you can simply include a reference to “upcoming topics,” without saying exactly when they’ll appear.