IIRC, we added a new query param to preauth so you should be able to specify the URL to redirect to. For example:
Code:
{existing-preauth-url}&redirectURL=/zimbra/h/ I think that should work. If not, can you please file a bug and we'll make sure to look at it before 4.5 ships?
thanks.
ps. I just tried it out on my local box and it worked fine. I'll update preuath.txt to document it.