SpamTitan Email Relay Configuration on cPanel Server
Update Domain DNS Record
DNS Setup MX Records for DNS
Update DNS
domain.com. - 14400 - IN - MX - 0 - cloud1.spamtitan.com.
domain.com. - 14400 - IN - MX - 10 - cloud2.spamtitan.com.
Set MAIL option to "Local Mail Exchanger"
Testing
https://www.wormly.com/test_smtp_server
For Single Domain on Server using SpamTitan (Option A)
For All Domains on Server using SpamTitan (Option A)
http://clients.hostingireland.ie/knowledgebase/2213/Mailserver-changes-to-only-accept-from-the-filter-systems.html
Exim (Use WHM Advanced Editor)
To configure Exim to only allow email from the filter servers for certain domains, you have to set in the RCPT ACL:
custom_begin_rcpt_hard_limit
deny
!hosts = *.spamtitan.com : *.holodyn.net : localhost
message = Please deliver mail to the address specified in the MX records for this domain.
You can setup the spamfilter_domains list earlier, reading it from a file, or database, or even hard-coding it.