What stops a business owner from abstracting away the underlying email provider and sending domain, so that their email campaigns can be up and running again in minutes if Mailchimp bans them? Thankfully there are several reputable email service providers...and most companies have more than one top-level domain associated with their name...so a legitimate business should be able to keep their email program running without exposing their neck to the mercy of a single bot (atleast until the issue is resolved by support). Real spammers would quickly get banned from all major providers (hopefully), and the content of the spam email would get machine-learned.