title: What does the PHP mail Reply-To header do?
body: <p>My PHP Mail headers are:</p>
  
  <pre><code>From: Writer's Tryst &lt;admin@writers-tryst.com&gt;
  Reply-To: The Charlotte Gusay Literary Agency &lt;rontornambe@yahoo.com&gt;
  X-Mailer: PHP/5.5.37
  MIME-Version: 1.0
  Content-type: text/html; charset=iso-8859-1
  </code></pre>
  
  <p>When I click the Gmail "to" button:</p>
  
  <p><a href="https://i.stack.imgur.com/WQCfT.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/WQCfT.png" alt="enter image description here"></a></p>
  
  <p>When I reply to this email, the mail is sent to the From address. I expected it to be sent to the Reply-To address. Is there any way to setup PHP mail to accomplish this? The documentation is not clear about what the Reply-To header actually does. </p>