title: Gmail ReplyTo not working with PHP Mailer
body: <p>I have been sending emails using PHP Mailer for a long time. 
  I use ReplyTo option. 
  Recently, I have noticed that in some email clients, when the ReplyTo is clicked, the email is sent to the From address and not the ReplyTo. (The from and Reply To addresses are not gmail addresses)</p>
  
  <p>The ReplyTo function seems to be working fine in Microsoft Outlook. 
  It also works fine Inbox app on my Android phone, as well as Yahoo mail. </p>
  
  <p>I send the email like this: </p>
  
  <pre><code>$DisplayName = "Sample Name";
  $Customer-&gt;CompanyEmail = 'xyz@example.com';
  $mail-&gt;Sender="...";
  $mail-&gt;SetFrom( "123345_123@example.com", $DisplayName . " [". $Customer-&gt;CompanyEmail . "]", false);
  $mail-&gt;AddReplyTo(trim($Customer-&gt;CompanyEmail), trim($DisplayName));
  $mail-&gt;AddAddress($ReplyToEmailAddress, "");
  </code></pre>
  
  <p>Is there any reason that ReplyTo does not work in Gmail? 
  <br><br>
  1. Incidentally, if I open the Gmail in Basic HTML mode, the ReplyTo works.<br>2. Another interesting observation, if $ReplyToEmailAddress is in my Gmail Contact list, Reply To works fine. </p>