How to block smtp of a single user in WHM
Use the following steps, login server with root user.
run below commands on terminal:
#cat /etc/blockeddomains #echo "block_domain.com" >> /etc/blockeddomains
Login WHM Panel and follow below procedure
Exim Advanced Editor > Section: CONFIG scroll down to “Add additional configuration setting”.
domainlist blocked_domains = lsearch;/etc/blockeddomains
Then scroll down to the Section: ROUTERSTART which is below the democheck entry and add:
reject_domains: driver = redirect # RBL Blacklist incoming hosts domains = blocked_domains allow_fail data = :fail: Connection rejected: SPAM source $domain is manually blacklisted.