Postfix is free open source mail transfer agent. The primary job of postfix is to pass on email locally or to intended location outside the system. Some of the most well-known SMTP web servers are Sendmail, Postfix and Qmail. By standard Sendmail comes pre-installed with CentOS/RHEL 5. We will need to remove it and set up Postfix.
yum remove sendmail yum install postfix
Use following command to make postfix as default MTA for your system:
alternatives --set mta /usr/sbin/postfix
If you get output as “/usr/sbin/postfix has not been configured as an alternative for mta“. Use below command to do the same else skip it:
alternatives --set mta /usr/sbin/sendmail.postfix
Now we are going to configure the postfix , Edit Postfix configuration file /etc/postfix/main.cf and make following changes:
myhostname = mail.cpanelplesk.com mydomain = cpanelplesk.com myorigin = $mydomain inet_interfaces = all mydestination = $myhostname, localhost, $mydomain mynetworks = 127.0.0.0/8, /32 relay_domains = $mydestination home_mailbox = Maildir/
Restart Postfix service to read the changes of settings. Also set up to automatic start on system boot.
service postfix restart chkconfig postfix on
Now add firewall rules to make postfix accessible from outside, using following commands:
iptables -A INPUT -m state --state NEW -m tcp -p tcp --dport 25 -j ACCEPT iptables -A INPUT -m state --state NEW -m udp -p udp --dport 25 -j ACCEPT
Congratulation , now you have postfix installed and you are all set to send email.