System information

118 Chapter 8 Customizing Services
About Junk Mail and Virus Filtering
Mail service can screen incoming mail before delivering it to check for viruses and junk
mail. Mac OS X Server uses SpamAssassin (spamassassin.apache.org) to analyze the text
of a message, and scores the probability of it being junk mail.
No junk mail filter is 100% accurate in identifying unwanted email. So Mac OS X Server
doesn’t delete junk mail. Instead it delivers the mail with “***JUNK MAIL***” added to
the subject. The recipient can decide if it’s really junk mail and deal with it accordingly.
Each message is analyzed and the word frequency statistics are saved. Mail messages
that have more of the same words as junk mail receive a higher score of probably
being junk mail.
Mac OS X Server uses ClamAV (www.clamav.net) to scan mail messages for viruses.
Email infected with a suspected virus is deleted, and a notice is sent to the notification
email address designated in the Information pane of Server Preferences. The server
automatically updates virus definitions once a day via the Internet.
Scanning for Incoming Junk Mail and Viruses
You can have mail service scan incoming messages for junk mail and viruses. Messages
containing known viruses are deleted. Messages suspected of being junk mail are
marked ***JUNK MAIL*** and delivered.
To have mail service scan for junk mail and viruses:
1 In the Mail pane of Server Preferences, select “Enable junk mail and virus filtering.”
2 Adjust the slider to set how tolerant the filter is of indications that an incoming
message is junk mail.
Aggressive: The junk mail filter tolerates few signs of being junk mail.