11 - To chroot or not to chroot
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Postfix can run most daemon processes in a chroot jail, that is,
the processes run at a fixed low privilege and with access only to
the Postfix queue directories (/var/spool/postfix). This provides
a significant barrier against intrusion. The barrier is not
impenetrable, but every little bit helps.
With the exception of the Postfix daemons that deliver mail locally,
every Postfix daemon can run chrooted.
Sites with high security requirements should consider to chroot
all daemons that talk to the network: the smtp and smtpd processes,
and perhaps also the lmtp client.
The default /etc/postfix/master.cf file specifies that no Postfix
daemon runs chrooted. In order to enable chroot operation, edit
the file /etc/postfix/master.cf. Instructions are in the file.
Note that a chrooted daemon resolves all filenames relative to the
Postfix queue directory (/var/spool/postfix). For successful use
of a chroot jail, most UNIX systems require you to bring in some
files or device nodes. The examples/chroot-setup directory has a
collection of scripts that help you set up chroot environments for
Postfix systems.
IMPORTANT: if you enable chrooted operation of the SMTP server you
must copy the passwd file into the chroot jail, otherwise the SMTP
server will reject mail for local addresses.
Likes: 
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