1. Create a file in /usr/mailscanner/etc/rules/ called scan.messages.rules
2. Put the following in that file and save the file:
FromOrTo: *@domain.com no FromOrTo: default yes
Add a line like the domain.com line above for any other domains you do NOT want to have ANY scanning - this includes virus, spam, phishing, dangerous html, and file attachment scanning.
If you want to whitelist incoming mail from a particular domain, you can use a line like this:
From: *@domain.com no
3. Go to WHM > MailScanner > MailScanner Configuration and set "Scan Messages = " to "%rules-dir%/scan.messages.rules" (without the quotes) and click Change.
Please note that the settings in WHM > MailScanner > MailScanner Front-End > Advanced Settings (Default for spam scanning, Default actions for high and low scoring spam, Default for virus scanning, and Default delivery action for virus infected email) will be the default settings for all domains on the server regardless of whether the cPanel front-end is enabled for them or not, except for domains that you have disabled scanning for by following the steps above.