how to quarantine ? really

I succeed to install qmail-scanner on my server.
 
Now, all messages are being scanned and x-report headers are there.
Subject is also changed when score is > 5.
 
But what I want is to keep all spam in a single mailbox.
So I will be able to access false positives from IMAP.
 
Plus, I want this mailbox to be keep clean.
Maybe I need a cron job.
 
Could somebody help me ?
I a newbie.
 
I tried to configure these variables;
my $sa_quarantine_site
my $smaildir_site="$vmaildir";
 
Without success.
 
Thanks a lot in advance.