title: What is a correct MIME type for .docx, .pptx, etc.?
body: <p>For older *.doc documents, this was enough:</p>
  <pre><code>header(&quot;Content-Type: application/msword&quot;);
  </code></pre>
  <p>What MIME type should I use for new .docx documents? Also, for pptx and xlsx documents?</p>