One thing you apparently can do right way, as a simple subscriber to god-knows-how-many newsletters handled by mailchimp, is to go to:
https://mailchimp.com/en/privacy-rights/
And at the very end send the form request a "Data Analytics Opt-Out" (and if you want, a data access or even data deletion right away).
There's a decent chance that what they're doing is illicit under the gdpr, but until someone files a complaint and they get fined, this is a concrete action.
Maybe ask your newsletter providers to switch from MailChimp as well, if you can dig out who they are...
So what they did, in the terms that take effect on November 16, is that among other things, at the new section 30 there's this:
We may use your Inputs and Outputs, including Customer Data, for machine learning purposes in order to develop and improve the AI Model, the Services, and similar products and features, and you instruct us to process Customer Data for such purposes. You may select preferences about your data by visiting your account settings.
So they'll feed the customers' data (our mail addresses, at the very least) into their AI model and other things, pretending that the MailChimp's client instructed them to do so, which of course, at least under the GDPR, could in all likelihood only legally happen after getting explicit consent from us newsletter subscribers.
So, it's at least almost for sure against the GDPR, but until they're stopped and fined they'll do it, and few of their clients (not to mention us newsletter subscribers) will realize anything.
And at the very end send the form request a "Data Analytics Opt-Out" (and if you want, a data access or even data deletion right away).
There's a decent chance that what they're doing is illicit under the gdpr, but until someone files a complaint and they get fined, this is a concrete action.
Maybe ask your newsletter providers to switch from MailChimp as well, if you can dig out who they are...