SSL explorer is a SSL VPN appliance. You authenticate to the SSL Explorer and it gives you access to the networks resoruces. You can create bookmarks to open pages on internal servers. The bookmarks are web forwards. The web forwards can be created using three diffrent methods; Reverse Proxy, Replacement Proxy or a Tunneled Forward. None of these seems to work with Zimbra, they all give the error I stated above. I am sure it has something to do with how the proxy does the calls to the server.
I might be able to put up a demo box for you to look at if you would like.
here a link to the SSL explorer web page
http://sourceforge.net/projects/sslexplorer/
We also have tried over the Sonicwall SSL-VPN 200, same issues.
Thanks, James.