I've been in touch with Mailchimp recently to ask if they've got any plans to issue its users with guidelines of what we need to do re. GDPR compliance; in regards to actual practical advice on setting up new lists etc, including any automated tools of theirs that might make things easier.
They said they're working with the people at GDPR direct at the moment to try and make sense of it all, and will be hopefully letting people know more info in due course.
This whole GDPR thing seems such a shambles to me; it's nowhere near enough time for small businesses to be able to dedicate appropriate time to get their stuff in order. Let alone people like us who run free networking events, in our spare time - which makes this all the more galling!
If I get any info from them (as they said they would be adding me to a list of people to send stuff through to) I'll let you all know, for all you fellow Mailchimp users.