Helo Guys, It would be really nice to have three options in Spamassasin settings Users&Email& (Spamfilter&Antivirus)=> Spam -- Accept Discard Move To Junk Folder -- as discussed here http://www.howtoforge.com/forums/showthread.php?t=15704
Remembering your post I wrote a small documentation about how to set that up. Hope that it pays out for you! http://www.howtoforge.com/how-to-add-a-move-to-spam-option-to-your-ispconfig-installation