Plesk 10 has an unique feature to blacklist and whitelist the desired email ids by the plesk administrator himself.
Please follow the below steps to Black List.
Login to the plesk control panel as admin and click on settings on LHS of the plesk panel.
Now scroll down to the Mail section, here click on Spam Filter Settings
After that go on the Blacklist tab and click on Add addresses
Now select From List and put the spam addresses in the adjacent box and click OK to enforce Black Listing on those addresses.
To create White List please follow the above mentioned First and Second Step and Then select White List tab and click on Add Addresses.
Now select From List and put the addresses in the adjacent box and click OK to unblock those addresses.