title: Email-Headers: Sender vs. x-sender
body: <blockquote>
    <p>If you want to "<a href="http://geekswithblogs.net/Lance/archive/2008/02/26/sending-email-on-behalf-of.aspx" rel="nofollow noreferrer">Send Email On Behalf
    Of</a>" someone else, should you use
    the 'Sender' heading or the 'x-sender'
    heading?</p>
  </blockquote>
  
  <p>Outlook 2007 seems to <em>only</em> pay attention to the 'Sender' heading, if it's present.</p>
  
  <p>On the other hand, there are those who believe that the 'Sender' heading <a href="http://webcache.googleusercontent.com/search?q=cache:iVVS0OvJ5sUJ:www.stopspam.org/index.php%3Foption%3Dcom_content%26id%3D45+x-sender+sender+unusual&amp;cd=2&amp;hl=en&amp;ct=clnk&amp;gl=us" rel="nofollow noreferrer">has been deprecated</a> in favor of the 'x-sender' heading.</p>