Defaults cannot be set for Spam and Virus delivery

Each mail-enabled domain in Virtualmin has a configuration screen for "Spam and Virus Delivery" which offers six choices for spam handling and five choices for virus handling.

However, under the Virtualmin Module Config, the default Spam filtering options can only be set to the first three choices for Spam (Delivery normally, delete, put in Spam folder) and first two choices for Virus (Delete, put in Virus folder).

I would like to configure the default behavior for Spam to be "Write to mail file under home directory" (the fourth option) with the setting "Maildir/.Spam/", but I cannot express this through the default configuration. Instead I must set this every time a domain is created.