How to blacklist IPs from connecting to the SMTP server

Introduction

Here are the full instructions to blacklist IPs from connecting to the SMTP server.  

Procedure

1. Log in to WHM as the root user.
2. Navigate to Service Configuration >> EXIM Configuration Manager:
3. Search for blacklist:
4. Locate Blacklisted SMTP IP addresses:
5. Select Edit:
6. Enter the IPs to blacklist.
7. Click Save: