You have two different types of subscribers on your email list. The folks who open your emails with some regularity and the folks who never open your emails at all.

I realize that each of those email addresses are hard-won. The problem is, the folks who never open your emails may be inadvertently harming your entire list.

Which is why you need a re-engagement email strategy, so you can get those folks back on board, or remove them from your list.