Coming from being a former MailChimp tech support agent (regular tech support, not compliance support), I can say that while I was in tech support, all account data is accessible on the company’s backend and for closed accounts, their data is available for 3 months after the close date. Open accounts aren’t pushed to dormant status until 2 years after no send and no login activity. Pretty happy that I’m no longer there; MailChimp was fine but they don’t pay their support agents enough for the kinds of stress and bad management they have to go through.