That's why you send a warning e-mail. You could also opt them down to a weekly digest instead of daily e-mails. One good thing about Sailthru is that it you ca

That's why you send a warning e-mail. You could also opt them down to a weekly digest instead of daily e-mails. One good thing about Sailthru is that it you can track all clicks on links. So if you have a user with no opens and no clicks over a few months, you have a lot more certainty that they're not reading (especially if your e-mails have a considerable amount of links).