Originally posted by serve-you.net
No. Plesk modifies the way that qmail runs, in order for it to integrate with the CP. Usually rebuilding qmail on a plesk box, means running a different queue, such as qmail-scanner, or some other "wrapper".
The patch you pointed out, does nothing special from what I can tell. Like I said before, just add a redirect to each user, and you will get the same thing.