You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <alltransclusions gatcontinue="Emailnav|1843" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1667" ns="0" title="1999-2000 Emails" />
      <page pageid="1668" ns="0" title="2000-2001 Emails" />
      <page pageid="1669" ns="0" title="2001-2002 Emails" />
      <page pageid="1670" ns="0" title="2002-2003 Emails" />
      <page pageid="1671" ns="0" title="2003-2004 Emails" />
      <page pageid="1825" ns="0" title="2004-2005 Emails" />
      <page pageid="1838" ns="0" title="2005-2006 Emails" />
      <page pageid="1839" ns="0" title="2006-2007 Emails" />
      <page pageid="1840" ns="0" title="2007-2008 Emails" />
      <page pageid="1841" ns="0" title="2008-2009 Emails" />
    </pages>
  </query>
</api>