title: Google Spreadsheet Script Editor MailApp.sendEmail not setting replyTo?
body: <p>I'm using Google Spreadsheet for customers to send in comments. When they submit a comment, it gets emailed to me. I use <a href="https://developers.google.com/apps-script/class_mailapp#sendEmail" rel="nofollow noreferrer">the MailApp.sendEmail method</a>. It works as expected except for the replyTo "advanced argument":</p>
  
  <pre><code>var myAdvancedArgs = { htmlBody: myHtmlBody, replyTo: customerEmail };
  MailApp.sendEmail("me@example.com", "Comments Form", myBody, myAdvancedArgs);
  </code></pre>
  
  <p>customerEmail is set properly because I have it output correctly in the body of the message. htmlBody works as I do get the HTML version of the email displaying in my GMail account. However, when I click the reply button in GMail, the To: address is myself. It appears the <code>replyTo</code> is not being set at all. But then I look in the headers of the email message by clicking the little triangle next to my name with the tooltip "Show Details" and it does mention the correct reply-to address:</p>
  
  <pre><code>reply-to:    mycustomer@example.com
  </code></pre>
  
  <p>Is <code>MailApp.sendEmail</code> not setting the reply-to header correctly?</p>
  
  <p><strong><em>UPDATE</em></strong>: I've snipped a couple images to demonstrate what's happening. Either the <code>reply-to</code> header isn't set properly (maybe that's not how you do a reply to?) or GMail is not working properly for me.</p>
  
  <p>First image, you see that there is a <code>reply-to</code> header created from my Google Spreadsheet script:
  <img src="https://i.stack.imgur.com/6Y9qS.png" alt="Email from script with reply-to header set"></p>
  
  <p>Second image, when I click the reply button in GMail, the to address is <strong><em>not</em></strong> filled in with the address in the <code>reply-to</code> header:
  <img src="https://i.stack.imgur.com/I1BFj.png" alt="Bad reply to address"></p>