title: Postfix Email server - Host name doesn't match IP address
body: <p>I've got a postfix mail server setup on my VPS.</p>
  
  <p>Just the other day when I sent an email I got it bounce back with the following error message:</p>
  
  <p><code>Remote host said: 454 5.7.1 DXNS3 208.81.237.186: Message refused. Your host name dosen't match with your IP address: mx6-out.gaggle.net</code></p>
  
  <p>Is this a problem with my server? By the way, my mail server isn't mx6-out.gaggle.net but it should be mail.onlythebible.com</p>
  
  <p>So I'm a little confused as to what this error message means and how I can solve it. Thanks for any help with this issue.</p>