after you’ve already done this: http://rln.d13dns.com/2014/07/19/djbdns-dnscache/
(if you’re not interested in a djbdns dns cache do the first two parts to install daemontools and ucspi)
Install outbound only qmail smtp service to your box with the following:
cd /var/tmp/ yum install gcc gcc-c++ make patch pam-devel openssl* wget -y yum install vim-common vim-enhanced autoconf automake -y wget http://www.qmail.org/netqmail-1.06.tar.gz tar zxf netqmail-1.06.tar.gz cd netqmail-1.06 mkdir -p /var/qmail/alias groupadd nofiles useradd -M -g nofiles -d /var/qmail/alias alias useradd -M -g nofiles -d /var/qmail qmaild useradd -M -g nofiles -d /var/qmail qmaill useradd -M -g nofiles -d /var/qmail qmailp groupadd qmail useradd -M -g qmail -d /var/qmail qmailq useradd -M -g qmail -d /var/qmail qmailr useradd -M -g qmail -d /var/qmail qmails make setup check ./config cat /dev/null > /var/qmail/control/rcpthosts echo ./Mailbox >/var/qmail/control/defaultdelivery cat > bin/qmailctl # cut and paste contents of script from 2.8.2.1 # http://www.lifewithqmail.org/lwq.html#start-qmail chmod 755 /var/qmail/bin/qmailctl mkdir -p /var/qmail/supervise/qmail-smtpd/log mkdir -p /var/qmail/supervise/qmail-send/log echo '#!/bin/sh' >/var/qmail/supervise/qmail-send/run echo 'exec /var/qmail/rc' >>/var/qmail/supervise/qmail-send/run echo '#!/bin/sh' >/var/qmail/supervise/qmail-send/log/run echo 'exec /usr/local/bin/setuidgid qmaill /usr/local/bin/multilog t /var/log/qmail' >>/var/qmail/supervise/qmail-send/log/run cat > /var/qmail/supervise/qmail-smtpd/run # cut and paste contents of script from 2.8.2.2 # http://www.lifewithqmail.org/lwq.html#start-qmail # if you get segfaults when you try to start qmail-smtpd # you need to increase the soft limit in this file (9000000) # did the trick for me # change the last line of the above script # change the "0 smtp" to "127.0.0.1 25" echo 5 > /var/qmail/control/concurrencyincoming chmod 644 /var/qmail/control/concurrencyincoming echo '#!/bin/sh' > /var/qmail/supervise/qmail-smtpd/log/run echo 'exec /usr/local/bin/setuidgid qmaill /usr/local/bin/multilog t /var/log/qmail/smtpd' >> /var/qmail/supervise/qmail-smtpd/log/run chmod 755 /var/qmail/supervise/qmail-send/run chmod 755 /var/qmail/supervise/qmail-send/log/run chmod 755 /var/qmail/supervise/qmail-smtpd/run chmod 755 /var/qmail/supervise/qmail-smtpd/log/run mkdir -p /var/log/qmail/smtpd chown qmaill /var/log/qmail /var/log/qmail/smtpd ln -s /var/qmail/supervise/qmail-send /var/qmail/supervise/qmail-smtpd /service echo '127.:allow,RELAYCLIENT=""' >>/etc/tcp.smtp /var/qmail/bin/qmailctl cdb echo '#!/bin/sh' > /var/qmail/rc echo >> /var/qmail/rc echo '# Using stdout for logging' >> /var/qmail/rc echo '# Using control/defaultdelivery from >> /var/qmail/rc echo '# qmail-local to deliver messages by default >> /var/qmail/rc echo >> /var/qmail/rc echo 'exec env - PATH="/var/qmail/bin:$PATH" ' >> /var/qmail/rc echo 'qmail-start "`cat /var/qmail/control/defaultdelivery`"' >> /var/qmail/rc chmod 755 /var/qmail/rc /var/qmail/bin/qmailctl stop ; /var/qmail/bin/qmailctl start