Nearly every Postx application can run with xed low privileges and no ability to Â
change ID, run with root privileges, or run as any other user.
Postx uses the conguration les main.cf and master.cf in /etc/postx/. When Server
Admin modies Postx settings, it overwrites the main.cf le.
If you make a manual change to the conguration le of Postx, Server Admin overwrites
your changes the next time you use it to modify the Mail service conguration.
The spool les for Postx are located in /var/spool/postx/ and the log le is /var/log/
mail.log. For more information about Postx, see www.postx.org.
If you use another MTA (such as Sendmail), you can’t congure Mail service with Mac
OS X Server administration tools.
To use Sendmail instead of Postx, disable the current SMTP service through
Postx, then install and congure Sendmail. For more information about Sendmail,
see www.sendmail.org.
Mail Screening
After a mail delivery connection is made and the message is accepted for local
delivery (relayed mail is not screened), the mail server can screen it before delivery.
Mac OS X Server uses SpamAssassin (from spamassassin.apache.org) to analyze the
text of a message, and gives it a probability rating for being junk mail.
No junk mail lter is 100% accurate in identifying unwanted mail. For this reason the
junk mail lter in Mac OS X Server doesn’t delete or remove junk mail from being
delivered. Instead, it marks the mail as potential junk mail.
The user can then decide if it’s really unsolicited commercial mail and deal with it
accordingly. Many mail clients use the ratings that SpamAssassin adds as a guide in
classifying mail for the user.
Mac OS X Server uses ClamAV (from www.clamav.net) to scan mail messages for
viruses. If a suspected virus is found, you can deal with it in several ways, as described
below. The virus denitions are kept up to date (if enabled) via the Internet using a
process called freshclam.
14 Chapter 1 Understanding Mail Service
