Problem with bb mailboxes and postfix

[Rene Scherer]

Hi all

I'm trying to get a cyrus system working with postfix and bboards.
Everything works fine with normal user mailboxes, but I don't seem to be
able to deliver anything to a shared mailbox.

I've added a new postfix transport mapping for a bb sub domain. E.g.:
----------------------------
bb.mydomain.com       cyrusbb:
----------------------------

Any email to bb+sharedmailbox at bb.mydomain.com is now processed via the new
cyrusbb transport:
----------------------------
cyrusbb unix - n n - - pipe flags=R user=cyrus
argv=/usr/lib/cyrus/bin/deliver -e -m ${extension}
----------------------------

According to the logfile the correct transport is picked and deliver is
called. However something is not passed in correctly and deliver fails:
----------------------------
Jun  8 23:59:12 gideon postfix/qmgr[5117]: 71F1711DA9:
from=<root at mydomain.com>, size=675, nrcpt=1 (queue active)
Jun  8 23:59:12 gideon poll.tcpip:  Done mail and news send/fetch
Jun  8 23:59:12 gideon postfix/pipe[5232]: 71F1711DA9:
to=<bb+sharedmailbox at bb.mydomain.com>, relay=cyrusbb, delay=2159,
status=deferred (temporary failure. Command output: 421-4.3.0 usage: deliver
[-C <alt_config> ] [-m mailbox] [-a auth] [-r return_path] [-l] [-D]_ 421
4.3.0 v2.1.9 )
----------------------------

I'm using cyrus imap v.2.1.9 and postfix v.1.1.11. Does anyone have a
similar configuration working?

Thanks very much,
Rene