Email filters can be setup to automatically deal with incoming mail is a number of ways. These filters are commonly set in two places.
You can setup filters in your email client (like Eudora or WebMail) that filter email when you check for new mail. These filters can be set to file messages in mailboxes, or delete the messages all together, based on a number of things like the contents of headers etc. If you commonly check mail with more than one client, then you need to setup these filters in each email client you use.
Another place you can put filters is at the point email arrives at SFU, and so these filters would be acted on before the mail was put in your system IN box. Because of this, these filters only need to be setup once and would be acted on no matter what email client you are using. They would take effect before any filters you may have setup in your email client.
This web page is used to setup the second type of email filter. The web page is somewhat limited in what sort of filters you can setup, but is a good way to deal with most SPAM mail.