One may access Microsoft Exchange service using the Outlook Web App. However, Internet Explorer 11 now only loads Outlook Web App Light regardless the user's choice during login. This is a known problem as described
here that indicates that "[t]his issue occurs because the
MSIE token is removed from the
user-agent string in Internet Explorer 11." The solution is to create a workaround, that is to use Internet Explorer 11
in compatibility mode to access OWA. "To do this, press F10 to display
the menu bar, go to the
Tools menu in Internet Explorer 11, and then click
Compatibility View settings. Then, add the OWA site to the list of sites to be viewed in compatibility view." as indicated in
the article.
The following is the User-Agent value obtained from a JavaScript's navigator object. The code snippet is as follows,
<script type="text/javascript">
document.write("<ul><li>UserAgent: "
+ navigator.userAgent + "</li></ul>");
</script>
You can observe and compare what the User-Agent value you obtain before and after switching to the Compatibility View.