[Exim] Single local delivery for multiple local users *or* L…

As I'm sure many people have brought to light, Cyrus has support for LMTP input
to it's 'deliver' program. In fact, this is *required* in order for the cyrus-
native vacation (Sieve) functionality.

Also, there are patches to the cyrus source base that allows a message to only
take up disk space once, and users mailboxes to have symlinks to the actual
data (like an exchange server)

It's the latter that interests me. In order for this to happen, the message has
to be passed exactly once to deliver, with the list of all local users on the
command line.

What I'm wondering is whether there'a a way of running a local deliver process
once for all the local users in the message. At the moment I'm using a pipe
transport set up as follows:


local_delivery:
driver = pipe
command = "/usr/cyrus/bin/deliver -q -e ${local_part}"
delivery_date_add
envelope_to_add
return_path_add
log_output
prefix =
suffix =
group = mail

What I'd like to do is:

local_delivery:
driver = pipe
command = "/usr/cyrus/bin/deliver -q -e ${list_of_all_message_local_parts}"
delivery_date_add
envelope_to_add
return_path_add
log_output
prefix =
suffix =
group = mail


And have that run once for each message with local users. Is this possible?

Cheers,
Phil