Norton AntiSpam 2004

Only for your info (I don't have it, so I cannot tell you about it from my own experience).

Norton AntiSpam 2004

http://www.symantec.com/antispam/
http://www.symantec.com/homecomputing/library/spam_22.html

Quote from the first link:
Symantec’s Norton AntiSpam™ 2004 filters unwanted email out of your inbox. Working with any POP3 email program, it filters incoming mail on multiple levels, detecting and flagging unsolicited messages while promptly delivering valid mail. To make your online time more enjoyable, Norton AntiSpam also blocks intrusive pop-up and banner ads.
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It is not free.

They say that it will also block ads.
At the moment I don't know (sorry !) whether you can add entries by yourself, nor whether you could perhaps use for example ProWAGoN from Eric Howes.