title: PHP Date format for MailChimp birthday field - whats the correct format?
body: <p>I am trying to update a subscriber with his birthday, but it won't accept any formats I've input.</p>
  
  <p>I've tried:</p>
  
  <pre><code>date('d/m/Y', time());
  date('d/m', time());
  date('m/d', time());
  </code></pre>
  
  <p>What's wrong? Their API documentation says:</p>
  
  <blockquote>
    <p>"the month and day of birth, passed as MM/DD"</p>
  </blockquote>
  
  <p>And:</p>
  
  <blockquote>
    <p>optional only valid for birthday and date fields. For birthday type,
    must be "MM/DD" (default) or "DD/MM". For date type, must be
    "MM/DD/YYYY" (default) or "DD/MM/YYYY". Any other values will be
    converted to the default.</p>
  </blockquote>
  
  <p>But it wont work! When imported, the birthday-field is blank.</p>