System information
137Chapter 9 Customizing Services
Scanning for Incoming Junk Mail and Viruses
You can have mail service scan incoming messages for junk mail and viruses.
To have mail service scan for junk mail and viruses:
1 In the Mail pane of Server Preferences, select “Enable junk mail and virus ltering.”
2 Adjust the slider to set how tolerant the lter is of indications that an incoming
message is junk mail.
Aggressive: The junk mail lter tolerates few signs of being junk mail.
Moderate: The junk mail lter tolerates some signs of being junk mail.
Cautious: The junk mail lter marks an incoming message as junk mail only if it
contains many signs of being junk mail.
Mac OS X Server uses SpamAssassin (spamassassin.apache.org) to analyze the text of a
message and score the probability of it being junk mail. Each message is analyzed and
word frequency statistics are saved. Mail messages that contain a higher number of
words found in junk mail receive a higher score for probably being junk mail. Messages
suspected of being junk mail are marked ***JUNK MAIL*** and delivered. The recipient
can decide if a message is really junk mail and deal with it accordingly.
Mac OS X Server uses ClamAV (www.clamav.net) to scan mail messages for viruses.
Messages suspected of containing viruses aren’t delivered but are stored on the server
in the /var/virusmails/ folder, and a notice is sent to the email address designated for
alert messages in the Information pane of Server Preferences. The server automatically
updates virus denitions daily via the Internet, and periodically deletes the mail in the
/var/virusmails/ folder.