Create back-up copies of any list, data, etc. that matters to you. I backed up my Mailchimp list a couple months ago with exactly this scenario in mind. It's a

Create back-up copies of any list, data, etc. that matters to you. I backed up my Mailchimp list a couple months ago with exactly this scenario in mind. It's a minor chore to do so. But it sure beats having years of data vanish.