How Spam Shredder Determines that an E-mail is Spam

The Spam Shredder engine uses two methods to determine if an e-mail is spam:

Rules—The engine looks at both the headers (which identify where the message came from) and the text of each e-mail message and applies rules that are characteristic of spam. Each rule in the engine carries a point value. As the engine compares the e-mail to its rules, it adds up the points. When the point value exceeds a predetermined value (spam threshold), Spam Shredder treats the message as spam and quarantines it.
Learning database—When you installed Spam Shredder, you also installed the pretrained learning database, which increases Spam Shredder's ability to identify spam. Spam Shredder compares incoming e-mail to the database to determine if an e-mail is spam. You can also send messages to the database as you review your quarantined and delivered e-mail. The learning database is a very powerful tool for "teaching" Spam Shredder what you consider to be spam and what you consider to be "good" e-mail.

In addition to these two methods that Spam Shredder uses automatically, you can add spam e-mail addresses to a blacklist. For more information, see Setting Up Known Spam E-mail Addresses (Blacklist).