MailScanner is the scanner program WebNameHost uses to block viruses and tag spam. It provides a new front end to drive SpamAssassin (which has been removed from the control panel) and many more tools. The MailScanner front end is available in the X (at the bottom) and RVSkin control panel skins. Note also that BoxTrapper has now been removed. Since most spam has forged return addresses, sending back a challenge to that forged address is regarded as spam (blowback spam) by most sites).
Please take some time to set up filters in your control panel for white and black lists, and otherwise filter spam after it arrives at your machine. remember that there will always be false positives (real mail that gets marked as spam) and false negatives (spam that gets missed). However, the system does gradually learn how to do a better job.