Learn to Install and Configure Postfix on Oracle Linux
This tutorial shows you how to install and set up the Postfix email server software on an Oracle Linux system to enable you to send messages within your network. This tutorial is targeted at users of Oracle Linux 8 or later.
Postfix is a Mail Transfer Agent (MTA) server that was developed as a replacement for
sendmail, which is the default MTA server on many older Linux systems. Because of its modular pipeline-based architecture, Postfix is versatile and integrates easily with many other services, such as spam and anti-virus processing, as well as with message store software, such as the Dovecot IMAP and POP server.
This tutorial describes how to set up and configure Postfix to function primarily as a Simple Mail Transfer Protocol (SMTP) server.
Upon completion of this Lab you will be able to:
- Set the server host name
- Install Postfix with appropriate firewall rules
- Configure Postfix to send unencrypted email
- Send test emails by using
- Review the Postfix mail queue
- Any system with Oracle Linux 8
Note: When using the free lab environment, see Oracle Linux Lab Basics for connection and other usage instructions.
postfixpackage on your instance by using the package manager, as follows:
sudo dnf install -y postfix
Allow SMTP traffic through the server firewall:
sudo firewall-cmd --zone=public --add-service=smtp --permanent
sudo firewall-cmd --reload
sendmailpackage, if it is present:
sudo dnf remove -y sendmail
Set Postfix as the default Mail Transfer Agent:
sudo alternatives --set mta /usr/sbin/sendmail.postfix
Enable and start the Postfix service:
sudo systemctl enable --now postfix
Create a backup for the default Postfix configuration:
sudo mv /etc/postfix/main.cf /etc/postfix/main.cf.bak
Edit the configuration file,
/etc/postfix/main.cf, to contain lines similar to the following:
sudo tee -a /etc/postfix/main.cf > /dev/null <<EOF myhostname = $(hostname -f) myorigin = \$myhostname inet_interfaces = all inet_protocols = all mydestination = \$myhostname, localhost mynetworks = 192.168.1.0/24, 127.0.0.0/8, 10.0.0.0/24 EOF
Note: Sending emails from a single host is sufficient for the purpose of this lab. In a production environment, you should set
mydomainas the registered domain name from which you intend to send email. For more information, read the Postfix manual pages.
Restart the Postfix service:
sudo systemctl restart postfix
Send Test Emails
sudo dnf install -y mailx
Send a test email to your own external email address. Update the hostname in the
mailxcommand to match the instance from which you are sending email:
echo "External email" | mailx -r root@$hostname -s "Test email subject" firstname.lastname@example.org
mailxto send test emails from a single host is sufficient for the purpose of this lab. In a production environment, you should use the registered domain that you configured in
/etc/postfix/main.cfwithin the sender email address instead, for example
Check your own email account for a new message. You may need to check your spam folder.
If the email does not appear, you can check the Postfix mail queue:
You can also check the Postfix log. Press Ctrl + C to exit:
sudo tail -f /var/log/maillog