How to stop Spam attacks on cPanel hosting server

Linux, being an open-source platform, is supported by a vast and diverse community. However, its widespread usage also attracts intruders who exploit vulnerabilities to perform malicious activities, such as compromising servers to leak information or disrupt operations.

To protect cPanel hosting servers from spam and malicious activities, it is crucial to implement effective security measures and configure essential tweaks.

Here’s how you can do it:

Step 1: Configure the Exim Mail Server

1. Log in to WHM
   Access the WHM control panel using your root login credentials.
2. Access Exim Configuration Manager
   Navigate to Service Configuration and select Exim Configuration Manager.
   
3. Enable RBL Filtering
   In the Basic Editor, turn the RBLs switch to On. Optionally, you can add additional RBLs using the “Manage” option.
   
4. Enable Sender Verification
   • Turn Sender Verification Callouts to On.
   • Turn Sender Verification to On.
5. Reject SPF Failures
   Turn the Reject SPF Failures option to On.
6. Save Configuration
   Save your changes to apply the settings. These steps will significantly reduce spam on the server.

Step 2: Adjust Tweak Settings

1. Log in to WHM
   Access the WHM control panel using root login credentials.
2. Access Tweak Settings
   Navigate to Server Configuration and select Tweak Settings.
   
3. Modify Email Settings
   • Set Initial default/catch-all forwarder destination to Fail.
   • Limit Max hourly emails per domain to 200.
   • Turn Count mailman deliveries towards a domain’s Max hourly emails to On.
   • Set The maximum percentage of failed or deferred messages a domain may send per hour to 60%.
4. Save Configuration
   Save your changes to finalize the settings.
   

By implementing these configurations, you can effectively reduce spam and protect your cPanel hosting server from malicious activities.