I setup preauth on our server so now there is a single login for both our intranet site and the zimbra server.

I want both the login and logout to be redirected to our intranet site.

I found this:
CASifying Zimbra 6.0 - Zimbra :: Wiki
But it states changing the urls to a .jsp page...?
what is that?
And what exactly is CAS?

Is this what I need to do to setup login/logout redirects?

How would I go about implementing this?