The first option, when set, can restrict sites that are allowed to send you e-mail. Click Allow e-mail from well-behaved servers (recommended for most users).
The next option, when set, will scan your e-mail by a program that tries to identify potential "spam" messages based on the content of the message. Click Scan e-mail with SpamAssassin.
To have a list of messages that were blocked from your account sent to your e-mail account on a periodic basis, locate the Blocked E-mail List Reporting section and choose an option.
Click Submit. A confirmation page appears.
For more information, go to SpamAssassin's home page.