[exim] Exim and delivery to Cyrus IMAP shared folder

I've been looking at delivery of incoming emails directly to a Cyrus
IMAP shared folder. Quite simply I'd like to know if this is possible?

I have a shared folder on Cyrus like this
share/pfstaff

Other user folders are under
user/staff1
user/staff2
etc...

Currently Exim will deliver directly to the user mailboxes using the
following router and transport

cyrus_vdom:
driver = accept
domains = +cyrus_domains
transport = cyrus_ltcp
no_more
...
cyrus_ltcp:
driver = smtp
protocol = lmtp
hosts = 127.0.0.1
allow_localhost

in /etc/cyrus.conf I have the following.
   lmtp          cmd="lmtpd -a" listen="lmtp" prefork=0
thus I know that Exim is delivering to Cyrus via unauthenticated LMTP.

If an email is sent to pfstaff I get and error reporting "550-Mailbox
unknown. Either there is no mailbox associated with this\n550-name or
you do not have authorization to see it.\n550 5.1.1 User unknown"

I've tried different combinations in /etc/mail/aliases of
"share.pfstaff", "pfstaff.share" "share+pfstaff" to no avail. Still the
same "550 5.1.1 User unknown"

I'd like to know if it is possible for Exim to deliver directly to the
mailbox share/pfstaff? and if so can someone suggest how this is
achieved? There are a number of discussions about this but I can't tell
from them if the final result I'm looking for has ever been achieved.

Regards.

--

Charles Dand

Penguin Factory Ltd
www.penguinfactory.co.uk
Tel:0845 868 3988

PenguinFactory Limited is a limited company registered in Scotland
registered in Scotland number SC270171. Registered office: Penguin
Factory Limited, c/o Sinclair Wood and Co. 90 Mitchell Street Glasgow.
G1 3NQ.