title: Configure CSF to allow outbound SMTP
body: <p>I have a web app that sends email via SMTP (Gmail, Zoho Mail servers). The thing is, the email sending works in my localhost but not on my VPS (using WHM).</p>
  
  <p>I contacted support and the guy replied: </p>
  
  <blockquote>
    <p>If your VPS has ConfigServer Firewall (CSF) installed then this would
    most likely be causing the problem. As it is working on localhost but
    not externally this certainly sounds like it might be the case. You
    will need to review the firewall configuration on the VPS and ensure
    hose ports are allowed outbound.</p>
  </blockquote>
  
  <p>But when it comes to server management and configuration, I'm totally lost. I did check the CSF settings page on WHM but not sure where to start.</p>
  
  <p>Any recommendation or solution would be appreciated.</p>