title: Resubscribe a user to a MailChimp list after unsubscribe
body: <p>My site allows users to subscribe to MailChimp lists using the API via Drupal MailChimp module. But if a user unsubscribes by following the link in the email, and subsequently decides to re-subscribe by visiting my website and checking the "subscribe" box, MailChimp responds with </p>
  
  <blockquote>
    <p>xxx@xxx.xxx is in a compliance state due to unsubscribe, bounce, or
    compliance review and cannot be subscribed.</p>
  </blockquote>
  
  <p>What is the solution assuming the user really wants to re-subscribe?</p>