Virtual users on Mac Os X server

[Wrack44]

Hi,

I'm quite new on Mac Os X server, I've already installed some mail servers with qmail on Linux without troubles, but if I can, I want to keep it easy and use the tools installed by Apple. My question is: I need to host some email addresses. Problem? I don't want to add a user on the system for each email address, I want to add virtual addresses (meaning that test@mydomain.com, test is not a user of the system, but is a valid email account (with IMAP access). Do you know if it is possible? I've checked many websites and tutorials, and they all install a system user per email address.

Thanks for you help,

BR