How to install postfix mail on centos 7

Here's a step-by-step guide to installing and configuring Postfix mail server on CentOS 7:

Step 1: Install Postfix

Open a terminal and run the following command to install Postfix:

sudo yum install postfix

This will install the Postfix package and its dependencies.

Step 2: Configure Postfix

Postfix configuration files are located in the /etc/postfix directory. You'll need to edit the main configuration file, main.cf, to set up your mail server.

Run the following command to edit the main.cf file:

sudo nano /etc/postfix/main.cf

Add the following lines to the end of the file:

myhostname = your_hostname
mydomain = your_domain
mydestination = $myhostname, $mydomain
mynetworks = 127.0.0.0/8 [::1]/128

Replace your_hostname and your_domain with your actual hostname and domain name.

Step 3: Create a Postfix user and group

Create a new user and group for Postfix:

sudo useradd -r postfix
sudo groupadd postfix

Step 4: Set ownership and permissions

Set the ownership and permissions for the Postfix configuration files:

sudo chown -R postfix:postfix /etc/postfix
sudo chmod -R 750 /etc/postfix

Step 5: Start and enable Postfix

Start the Postfix service and enable it to start automatically on boot:

sudo systemctl start postfix
sudo systemctl enable postfix

Step 6: Configure the Postfix daemon

Edit the Postfix daemon configuration file, master.cf, to allow the daemon to listen on port 25:

sudo nano /etc/postfix/master.cf

Add the following line to the end of the file:

25 inet n - - - smtpd

Step 7: Restart Postfix

Restart the Postfix service to apply the changes:

sudo systemctl restart postfix

Step 8: Test Postfix

Use the telnet command to test Postfix:

telnet localhost 25

You should see a response from Postfix indicating that it's listening on port 25.

Step 9: Configure your mail client

Configure your mail client (e.g., Thunderbird, Outlook) to use your Postfix mail server. You'll need to set the server name to localhost or your_hostname, and the port to 25.

That's it! You should now have a basic Postfix mail server up and running on your CentOS 7 system.