This is the most important interface. It is used directly by client programs. It is the core of the system. This module is responsible for integration with a mail transfer agent. Usually this module creates and maintains data structures on disk, MTA's configurations, etc.
It represents all functions system offers. Client applications connect to it using CORBA protocol and call its methods.
Ivq module calls methods from iauth interface to retrieve or store informations about users or domains.
At this time there's only one implementation of ivq represented by cqmailvq class, and by qmailvqd daemon.
This object integrates with qmail MTA. It handles updating qmail's configuration, managing users' maildirs, directories hierarchy, etc.
For some actions it uses small, helper programs that are responsible for qmail's configuration updates. This way privileges can be separated - qmail's configuration can be owned by a user other than the user which runs qmailvqd.