I recently came across some old perl docs for Virtualmin from 2012... call me nostalgic... : )
SET-SPAM(1) User Contributed Perl Documentation SET-SPAM(1)
set-spam.pl
Change the spam and virus scanners for all domains
By default, Virtualmin uses the stand-alone ClamAV and SpamAssassin
programs for virus and spam scanning, named "clamscan" and
"spamassassin" respectively. However, on a system that receives a
large amount of email, running these programs for each incoming message
can generate significant CPU load.
This command can tell Virtualmin to use the background scanning daemons
"clamd" and "spamd" instead, which are faster but consume additional
memory as then run all the time. To enable the ClamAV server, run it
like so :
virtualmin set-spam --enable-clamd
virtualmin set-spam --use-clamdscan
To enable and use the SpamAssassin daemon process, run the commands :
virtualmin set-spam --enable-spamd
virtualmin set-spam --use-spamc
However, using "spamc" makes it impossible to have separate per-domain
SpamAssassin configurations in Virtualmin.
perl v5.10.1 2012-08-24 SET-SPAM(1)