title: How to handle "Domain of sender address ee@e.com does not exist" error exception
body: <p>I want to make this message <code>"Domain of sender address ee@e.com does not exist"</code> shows to client instead of debug error. How can I make it?</p>
  
  <p>In default, following debug error message is show.</p>
  
  <pre><code>Swift_TransportException
  Expected response code 250 but got code "553", with message "553 5.1.8 &lt;ee@e.com&gt;... Domain of sender address ee@e.com does not exist "
  </code></pre>
  
  <p>I want to make this error message shows to client to tell them their email address is not exists, please try others. How to handle this error message?</p>