Incredibly insightful, thank you for taking the time to post this!

> - Don't send to addresses where you have not contacted them or had any interaction at all for > 1 year. If you haven't kept in touch with your customers, then that is on you.

That seems odd though. "Keeping in touch" in regular intervals is exactly the kind of thing customers may want to unsubscribe from, so a working unsubscribe function means there are customers where I cannot keep in touch. How is that on me? That means I can't send e.g. a password reset email to them if they try to log in two years later?