Spamassassin is not spam blocker. It mark messages "as spam" or "is not spam". User need configure email client (MUA) for sorting spam messages to own "Junk" folder.
For effective spam blocking please use
Greylisting and
DNSBL lists such as bl.spamcop.net and zen.spamhaus.org, you can enable it in the Server configuration - Features and Spam protection - Dnsbl block lists menus