3. Click on ConfigServer Security & Firewall.
The CSF application will open.
4. Select the csf tab and click the Firewall Configuration button in the csf- ConfigServer Firewall section.
The ConfigServer Firewall’s configuration interface will appear.
5. Select the SMTP Settings section and click the Off switch for the SMTP_BLOCK field.
6. Scroll to the end and click on the Change button.
It will save the changes you made.
7. Click the Restart csf+lfd button.
It will restart the CSF application and apply the changes you made.
With this, the CSF Firewall will stop blocking all the outgoing SMTP for your WHM/cPanel server.
