I recently got an email from a mailing list saying "goodbye" to me because I don't read their emails anymore.

Of course, the catch is, I open their emails several times a week: I just block remote images. I replied back to them to tell them I don't appreciate them trying to track whether or not I open my mail in my inbox, but to keep me on the list.

I could get upset and unsubscribe because I'm annoyed they're relying on tracking, though FWIW, my experience demonstrates their tracking isn't working. And hopefully, me directly communicating with them that their strategy is both ineffective and unappreciated may help nudge them away from this sort of behavior.