As of March 21st 2019, the Mailchimp for Shopify integration has been removed from the Shopify Marketplace. For existing connected users, the integration will remain in effect through May 12th.
View Mailchimp's official statement
Learn more about Mailchimp's changes to their integration with Shopify, instructions to sync your contact lists, and manual workarounds for marketing features.
As far as we know, the 'Form Action URL' setting of the Turbo theme will continue to function for adding email address submissions to a List on Mailchimp. We will keep you posted on the best next-steps for your email service integration as we learn more about how the integration with Shopify and Mailchimp will be affected.
When a customer signs up on your theme's email newsletter form, their email addresses is added to your Shopify customer database. To send emails to them, you will need a third party email marketing provider and an app to sync between the provider and your store.
To automatically send email newsletter signups or customer email addresses to your email marketing provider, the best way is to use your provider's official app.
Below are links to some major email providers who have apps available:
Please note that if you encounter questions or concerns about installing, setting up or syncing email addresses using these apps, we recommend contacting your email marketing service's support team.
If you don't see your email marketing provider in the list above, you may want to try searching the Shopify App Store manually in case one has been released since this list was updated.
There are also third party developers that provide integrations with many email marketing providers not listed above. Please note there is an additional fee for these apps and these apps have not been reviewed or tested by Out of the Sandbox. For installation or support, please contact the app developer directly.
If you prefer not to use an app but your email provider provides embeddable signup forms, you can customize your code using these steps.