I decided not using ClamAV because the mail users are having already anti-virus programs on their workstations.
In Virtualmin -> Edit Virtual Server -> Enables features - I unchecked Virus filtering enabled?. I saved Virtual Server.
In Virtualmin -> Email Messages -> Spam and Virus Scanning - I click on Disable ClamAV Server
Let's do a Re-Check Configuration. Here is the error message at the end because system is not ready for use by Virtualmin: "You have selected to use clamdscan for virus scanning, but the clamd server it talks to is not running".
Let's do a Re-Run Install Wizard and disable ClamAV. Re-Checking again configuration we get the same eror message.
Why do I have to go and disabling from "Features and Pluging" Virus Filtering in order to fix this error?