I now also tried:

<http://user:pass@www.kaufmich.com/user/login?>postfile:C:\My%20Web%20Sites\KM\hts-post0>
-*
+http://www.kaufmich.com/forum

in order to exclude everything, but include the forum. However this does not
work. I can see that the login worked, but when I click on the forum link the
browser switches from offline to online mode and I need to log in.