Kvdomain hash /etc/vdomain
The /etc/vdomains.db database file holds the mappings to turn virtual addresses into real mailbox names. Database files are created with makemap. Entries in this file look like this:
joe virtual.com fred firstname.lastname@example.org larry custom.net
This is quite flexible. In this example, anything to anyone in virtual.com goes to joe, anything to "email@example.com" goes to fred, and anything else for custom.net goes to larry.