If subscribers are not being sent to your Mailchimp list or you see a "Sending subscribers failed" message,
verify that you have connected Mailchimp properly.
There are two main reasons that can cause a problem with the connection.
Have you used this email before? If you are testing the connection to Mailchimp with an email you already used, Mailchimp will not accept it
even if you already removed it from the list. You must use a different email address every time.
Your list settings has required fields which means Mailchimp doesn't allow us to add new subscribers to your list.
To resolve this either create a new list that only requires the email field or edit the current list to no longer require the extra fields. You can do that on the list settings page in the "merge fields" page
in your Mailchimp dashboard.
Either your account with Mailchimp is inactive or the mailing list has been deleted.
To fix this problem, please go to the app's settings window, click the Disconnect button to disconnect Mailchimp and then click to login with your Mailchimp account again.
Then, please test the form using a real email address and make sure that email address makes it to Mailchimp.