You can improve accuracy of spam detection by training the spam filter on the e-mail messages that you have in your mailbox.
To improve accuracy of spam detection:
All e-mail messages you have in your mailbox are presented on the screen.
Note: In Parallels Plesk Panel for Linux/Unix platforms, each message is accompanied by an icon in the left column, which tells if a message is recognized as spam - , non-spam - , or not recognized at all - . If you have already trained your spam filter on a message and the results were recorded in the spam filter's database, an icon is shown in the right column.
In most cases, you can tell if a message is spam by looking at its subject line and sender's name. If they do not give you any clue, try looking inside the message using your e-mail program or Webmail interface.