In your cPanel (if provided) next to each domain listed in the Spam scoring section at Anti SPAM Manager, you can set the spam filter sensibility.
"Normal" is the default Antispam server sensibility level.
You can decrease it using "low", "lower" and "lowest".
If you decrease the sensibility more spam could pass however you reduce the risk to block a good email.
You can increase it using "high", "higher" and "highest" to block more spam as possible.
If you increase the sensibility you can succeed to block all the spam, however you have a chance that a good email could be collected in spambox (assuming you have spambox@ enabled).