Postfix Configuration for a Linux PC. See also http://www.postfix.org/STANDARD_CONFIGURATION_README.html

/etc/postfix/main.cf

# only for local clients - mostly cron jobs
inet_interfaces = localhost
# local delivery 
mydestination = $myhostname, localhost.$mydomain, localhost
myorigin = $myhostname
masquerade_domains = src.wits.ac.za

# relay without slow DNS lookups
relayhost = [schonlan.src.wits.ac.za]
# do not modify the rest of main.cf

Using sSMTP instead of sendmail

on the clients, to make a simpler setup, and no running daemon.

sSMTP RPM page on pbone

sudo yum install -y ssmtp
sudo perl -i -p -e 's/^mailhub.*$/mailhub=psi/' /etc/ssmtp/ssmtp.conf
sudo rpm -e sendmail

On the psi server, change Postfix's mydestinations in main.cf to accept mail from these machines:

mydestination = $myhostname, localhost.$mydomain, localhost, regexp:/etc/postfix/mydestinations

and /etc/postfix/mydestinations:

/.*\.local/ localhost