title: Can I add custom Message-ID and In-Reply-To header using phpmailer?
body: <p>I am using <a href="http://phpmailer.worxware.com/" rel="nofollow">phpmailer</a> for sending emails, I am attempting to add <code>In-Reply-To</code> in email header but I can't. How can I achieve this? Can I use any <code>message-ID</code> or references when I am sending a email? Is there anything else to add <code>references</code> or <code>In-Reply-To</code> in phpmailer?</p>
  
  <p>So far I have tried to add below line in phpmailer</p>
  
  <pre><code>$mail-&gt;AddCustomHeader("In-Reply-To: ")
  </code></pre>
  
  <p>but it's not working. I also tried to change the return path code like</p>
  
  <pre><code>$mail-&gt;ReturnPath = 'bounce_here@domain.com';
  </code></pre>
  
  <p>but it did not change the return path as well.</p>
  
  <p>And one more things, Can I get the <code>message id</code> by using <code>imap</code> php?</p>