qmail, zarafa - mail delivery problem

[grim_reaper]

I use Plesk 8.3 on a Suse 10.1 64 Bit System.
I only have about 25 clients (not much) and all use Horde webmail in Plesk which is pretty good.
A few of them now wanted a Exchange like System so that they can sync their PDAs in Real Time, run Outlook as exchange and also have a webmail that looks like Outlook.

What I did so far:
So I installed Zarafa an after a few problems the server is now running. I'm able to connect via Webmail, I can run Outlook as Exchange and I can connect via LiveSync to my PDA. (Contacts, Notes and Calender entries already sync with each other!)

The Problem.
The Problem now is, that I'm just not able to send OR receive any emails on the Zarafa accounts. (the Horde accounts created through Plesk still work fine)
For Some reason qmail handles something wrong, I just don't know what :-(

The Zarafa Manual says:

Delivery of email through the server
To deliver an email into a user's inbox, you need to use the zarafa-dagent program. The
zarafa-dagent will read an SMTP email message from the standard input or a file. A parameter
to the zarafa-dagent is needed to select the store where to deliver the incoming message. A few
examples are given for different email servers:

qmail
Place in your $HOME/.qmail file a line containing:
| /usr/bin/zarafa-dagent -q [user name]
The [user name] tag needs to be replaced with the name of the user to correctly deliver the
email. The -q switch is to notify the zarafa-dagent program to return qmail style error codes. When
an email can temporarily not be delivered, it will stay in the qmail queue, which will try to deliver
the email later again.

The problem is that there a many many .qmail files in Plesk 8 which are all stored unter /var/qmail/mailnames/DOMAIN_NAME/NAME

The thing is I have absolutely no Idea how to configure qmail :-(
It would be really great if someone could give me a hint!

Oh, and of course, here's the qmail error log:

Jan 20 12:09:43 v1849 qmail-queue-handlers[22143]: starter: submitter[22144] exited normally
Jan 20 12:09:43 v1849 qmail-local-handlers[22146]: Handlers Filter before-local for qmail started ...
Jan 20 12:09:43 v1849 qmail-local-handlers[22146]: [email protected]
Jan 20 12:09:43 v1849 qmail-local-handlers[22146]: [email protected]
Jan 20 12:09:43 v1849 qmail-local-handlers[22146]: cannot reinject message to '[email protected]'
Jan 20 12:09:43 v1849 qmail-queue-handlers[22157]: Handlers Filter before-queue for qmail started ...
Jan 20 12:09:43 v1849 qmail-queue-handlers[22157]: from=
Jan 20 12:09:43 v1849 qmail-queue-handlers[22157]: [email protected]
Jan 20 12:09:43 v1849 qmail-queue-handlers[22157]: hook_dir = '/var/qmail//handlers/before-queue'
Jan 20 12:09:43 v1849 qmail-queue-handlers[22157]: recipient[3] = '[email protected]'
Jan 20 12:09:43 v1849 qmail-queue-handlers[22157]: handlers dir = '/var/qmail//handlers/before-queue/recipient/[email protected]