As of March 21st 2019, the Mailchimp for Shopify integration has been removed from the Shopify Marketplace.
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.
Please note that if you encounter questions or concerns about installing, setting up or syncing email addresses using MailChimp or any other Email Marketing service, we recommend contacting their support team.
To enable your Email Marketing integration:
Head into Online Store > Themes > Customize > Theme settings > Newsletter.
This tab will look something like this:
By default, your Newsletter's URL is not active. To activate this, you will need to find your Newsletter form action URL, which can be found in your email marketing account (ex. MailChimp account).
To activate your Email Marketing integration please follow the following steps (the ones shown here are for MailChimp, but other email marketing integrations should be similar):
1) Login to your Email Marketing account.
First thing is first, you will need to login to your Email Marketing account.
2) Head into your list, or create a new one.
If you are familiar with MailChimp and you have already created your list you can skip this instruction, otherwise from the MailChimp dashboard, please click "create a list".
3) What's a list?
Think of a list as where you will be sending all our your newsletter subscribers! After you have entered your information for your list you will be presented with your listing as shown here, for this example I called my list "My List".
4) Grabbing your Newsletter form URL.
To grab your MailChimp list URL you will need to click into the list you have just created or an existing list on your MailChimp account, once you have done so you can click the "Signup Forms" tab. After clicking this link your page should look like the following:
Once you are presented with this page please click into the embedded forms option by hitting the "select" button to the right.Your form action URL is available within the embeddable form code snippet from your email marketing provider - you don't need the entire snippet; simply grab the URL that follows form action=" , as shown here with MailChimp:
5) Adding your URL to your theme options
After you have grabbed your Newsletter list URL you can head back into your theme options found in Online Store > Themes > Customize, here you can navigate to the "newsletter" tab and add in your lists URL:
Once you have added in your lists URL, please save your theme options. You have now successfully added your Email Marketing Integration into your theme!