How to allow users to bypass CSF's SMTP_BLOCK

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Introduction

There may be times when you want to keep CSF's "SMTP_BLOCK" setting enabled while allowing certain users to send mail through external mail servers. This article provides the steps to configure CSF for this. 

Procedure

1. Log in to WHM as the ‘root’ user.
2. Navigate to "Home / Plugins / ConfigServer Security & Firewall."
3. Click the "csf" tab.
4. Click the "Firewall Configuration" button.
5. Select "SMTP Settings" from the dropdown menu.
6. Scroll down to the "SMTP_ALLOWUSER" setting.
7. Add the cPanel user's username in the "SMTP_ALLOWUSER" textbox.
   Please note that usernames must be separated by a comma.
8. Scroll to the bottom of the page.
9. Click the "Change" button.
10. Click the "Restart csf+lfd" button.