How To Change Hostname and SMTP Banner in Postfix on Plesk

In this tutorial, I'll guide you through the steps to change the hostname and SMTP banner in Postfix on your Plesk server. This process is essential for setting up email functionality properly. Let's see how we can get this done.

Prerequisites

• Access to your Plesk server via SSH.
• Basic knowledge of using terminal commands.
• Ensure you have a backup of your current configuration.

Step 1: Connect to Your Plesk Server

First, connect to your Plesk server using SSH. You can do this using the terminal or any SSH client:

ssh username@$server-ip

Step 2: Gather DNS Information

You may need to check your server's DNS records. Use the following commands to retrieve the necessary information:

dig PTR server.example_domain.com

dig A server.example_domain.com

host $serverIP

Step 3: Backup Postfix Configuration

Before making any changes, it's crucial to back up your Postfix configuration file:

sudo cp /etc/postfix/main.cf /etc/postfix/main.cf.backup-$(date +%Y-%m-%d)

Step 4: Edit the Postfix Configuration

Open the main configuration file in a text editor. Here, we'll use the vi editor:

sudo vi /etc/postfix/main.cf

Look for the parameters myhostname and smtpd_banner. Add or modify them as follows:

        myhostname = server.example_domain.com
        smtpd_banner = $myhostname ESMTP $mail_name
    

Important: Make sure to comment out (disable) any other instances of myhostname and smtpd_banner to avoid conflicts.

Step 5: Save Changes

After editing the file, save your changes and exit the editor.

Step 6: Check Postfix Configuration Syntax

Before restarting Postfix, verify that the configuration syntax is correct:

postfix check

If there's no output, this means the syntax is okay.

Step 7: Restart Postfix

Finally, restart the Postfix service to apply your changes:

sudo systemctl restart postfix

Troubleshooting Tips

If you encounter issues, ensure that:

• You have the correct DNS settings.
• Backup files are stored safely before making changes.
• You check the Postfix logs for any error messages.

Disclaimer

Always test changes in a safe environment before applying them to your production server. For the latest documentation, please refer to the official Plesk and Postfix documentation.