although the options "keep news younger than 10 days" and "remove bodies older than 11 days" are set the file the news are stored in gets bigger every day. Expected: File should stay more or less the same size Mozilla/5.0 (Windows; U; Windows NT 5.0; de-AT; rv:0.9.9) Gecko/20020311
Do you have the setting to compact folders automatically when it will save XXX Kb set? I'm assuming you're talking about the file the bodies of the news messages are stored, and not the headers (.msf file).
Ok, thanx that fixed the issue, however Mozilla marked all unread messages as read, but I think I've seen a bugreport for this before.
Compacting marking unread as read -- see bug 100781.