Set up an SMTP server on CentOS 7

To set up an SMTP server on CentOS 7, you can use a popular mail server software called Postfix. Here are the steps to install and configure Postfix:

1. Update System: Make sure your system is up-to-date by running the following commands:

sudo yum update

2. Install Postfix: Install the Postfix package using the following command:

sudo yum install postfix

3. Configure Postfix: Once installed, open the Postfix main configuration file in a text editor. For example:

sudo nano /etc/postfix/main.cf

Update the following parameters with your desired values:

myhostname = your_server_hostname
mydomain = your_domain.com
myorigin = $mydomain
inet_interfaces = all
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain

Save the changes and exit the text editor.

4. Start Postfix Service: Start the Postfix service and enable it to start on boot:

sudo systemctl start postfix
sudo systemctl enable postfix

5. Firewall Configuration: If you have a firewall enabled, allow traffic on the SMTP port (default is 25):

sudo firewall-cmd --permanent --add-service=smtp
sudo firewall-cmd --reload

6. Testing: You can test your SMTP server using the telnet command. Replace your_server_hostname with your actual server hostname:

telnet your_server_hostname 25

If everything is configured correctly, you should see a response from your SMTP server.

That's it! You have now set up a basic SMTP server using Postfix on CentOS 7. Make sure to check the Postfix documentation for more advanced configurations and security measures.