Postfix is a popular and powerful open-source Mail Transfer Agent (MTA) used for email delivery. Configuring it on a CentOS 7 system allows for flexible management of email traffic with a high level of control over email sending. This article provides a step-by-step guide on how to install and configure Postfix for basic email delivery.

Installing Postfix

Before you begin, ensure that your system is up to date. You can achieve this by running the command sudo yum update in the terminal. Once the updates are completed, you can proceed with installing Postfix:

1. Install Postfix by running sudo yum install postfix.
2. After installation, enable Postfix to start automatically at system boot using sudo systemctl enable postfix.
3. Then start Postfix using sudo systemctl start postfix.

Configuring Postfix

For basic Postfix configuration, you need to modify its main configuration file, main.cf, located in the /etc/postfix directory.

1. Open the configuration file in a text editor, such as by using sudo nano /etc/postfix/main.cf.
2. Set myhostname to the fully qualified domain name (FQDN) of your server, for example, myhostname = mail.yourdomain.com.
3. Set mydomain to your domain, for example, mydomain = yourdomain.com.
4. myorigin should be set to /etc/mailname. Ensure that this file contains your domain.
5. Set inet_interfaces to all to allow Postfix to listen on all network interfaces.
6. For simplicity, initially set mynetworks to 127.0.0.0/8, limiting email sending only from the local system.

After making these changes, save the file and restart Postfix using sudo systemctl restart postfix.

Testing Postfix

To test that Postfix is functioning correctly, you can send a test email from the command line:

1. Use the command echo "Test email from Postfix" | mail -s "Test Postfix" This email address is being protected from spambots. You need JavaScript enabled to view it., replacing This email address is being protected from spambots. You need JavaScript enabled to view it. with your actual email address.
2. Check your email to see if you received the test message.

The installation and basic configuration of Postfix on CentOS 7 are relatively straightforward. Postfix offers many configuration options to tailor the MTA's behavior to your email traffic needs. For advanced setup and security, it's recommended to familiarize yourself with the official Postfix documentation.