Anti-spam is a services and solutions that focus on blocking and mitigating the effects of illegal emails or spam on email users. There are different types of anti-spam systems have been integrated with the email systems of many email and Internet service providers (ISP). You can also set an anti-spam using terminal after ssh to the nameserver.

First, go to exim directory by executing

cd /etc/exim

Second, go to edit mode and add the desired domain by typing

vi relay-domains

Next, add the ip address of the domain in a different edit mode by typing

vi manual-routes

Lastly

service exim restart