mail forward without mailbox

[doddel]

current ISPConfig situation:
forwarding of mail to another address is now a feature linked to mail users.
I.e. to forward a mail directed to xxx@site one has to create a user xxx of the site.

wish situation:
The forwarding should not be forcibly coupled to users with passwords, mailboxes, and webspace. The client to which the site belongs should be able to set mail forwards such that any mail entering the server that corresponds to a forward prefix@site gets forwarded right away without further processing and without a need for reserving space for mailboxes etc.
It should also remain a feature to activate forwarding for the mail accounts of users.

The wish situation I do currently have on a VPS with Virtuozo full featured config panel which I am changing for a 'simple' VPS with ISPConfig.