TheCrimsonHorror

I had a customer today that wanted to block an account from being able to send email because they were dealing with a hacked website that was spamming. 

There is no specific feature in WHM/cPanel to just block a complete domain from being able to send mail, so I used the following process:

Created a new file called blockeddomains with the domain that I wanted to block 

echo "domain.com" > /etc/blockeddomains

Now setting the proper permissions / ownership for the file:

chown root.mail /etc/blockeddomains && chmod 640 /etc/blockeddomains

Now I have to tell EXIM to look at this file, and use it to deny email from the domains listed in it. 

Open WHM, and Browse to WHM >> Service Configuration >> EXIM Configuration Manager >> Advanced Editor
Scroll down to the Add additional configuration setting button, and click on it, and add the following: 

domainlist blocked_domains = lsearch;/etc/blockeddomains

Scroll down further to the ROUTERSTART section and add the following:

reject_domains:

driver = redirect
domains = +blocked_domains
allow_fail
data = :fail: SPAM Source rejected: $domain is manually blacklisted.

Now you can block/unblock any domains simply by editing the /etc/blockeddomains file.