If your Contacts List screen has been customized, the MailChimp integration may not be visible.
You can turn it on for the your Contacts grid, but the following columns are required to be in the grid:
The columns do not need to be visible, but they do need to exist in the grid.
Enabling the Send to MailChimp option:
Navigate to your Contacts List screen in the Contacts App (or any screen with a list of contacts you want to enable this option on).
Click the dropdown arrow [
⌄] beside the title of the app, and select Customize Screen.
Edit the screen and make a copy of it (if needed).
Within the ListSection section, select the ContactsGrid control.
On the right properties panel, under Settings, uncheck the checkbox Hide Send to MailChimp.
Save the screen and then Close it.
Remember to publish the screen so it's live for all users.
MailChimp is now available from the export icon.