A virtual domain is created by the command vadddomain(1).
% vadddomain example.com some_password
The above command creates a virtual domain with delivery instructions in /var/indimail/domains/example.com/.qmail-default file. A line in this file is of the form
/var/indimail/sbin/vdelivermail '' delivery_instruction_for_non_existing_user
The delivery_instruction_for_non_existing_user can have one of the following 5 forms