In Impeka, you can easily use the Contact 7 Form with an external plugin in order to use your MailChimp account in your site. We have tried 2 different plugins in Impeka, the MailChimp extension and the Contact Form 7 Mailchimp . Both work just fine so this way, you can easily use the well-known Contact 7 Form plugin to connect with your MailChimp account.
You can read more about the MailChimp integration on this article.