Blacklist an e-mail
If you are receiving spam that should be filtered...Login to http://login.postini.com
Click on "My Settings"
Click on "Block Senders"
Enter the e-mail under "Blocked Senders"
NOTE: This will take affect even if the e-mail address is in the white-list. This option should be used as a last resort.
The same process can be used to allow addresses, but select approve senders, instead of block senders.