Ultimate Member MailChimp GPL Overview:

This extension integrates MailChimp with Ultimate Member and allows users to subscribe to your mailing lists when they register on your site.

Ultimate Member MailChimp GPL Features:

• Automatically add users to a MailChimp list when they register.
• Allow users to opt-in to subscribing to a MailChimp list when they register.
• Add multiple lists to the register form and allow users to select which lists they subscribe to.
• Show different lists on different register forms.
• Sync user meta with MailChimp list.
• Allow users to subscribe/unsubscribe from their account page.
• Restrict lists to certain roles (Only roles that can subscribe/unsubscribe to a list will see it on their account page).