[Exim] pipe transport

we currently have some weird problems with our imap server. from time to time
it refused to work properly (segfaults). We are beginning to see a pattern...
anyway - that's not exim related...

...now comes the exim part: we use the pipe transport to deliver the mail:

local_delivery:
driver = pipe
command = "/usr/sbin/cyrdeliver ${local_part}"
return_output
log_output
prefix =
suffix =
user = cyrus
group = mail
home_directory = /tmp

local_lists_delivery:
driver = pipe
command = "/usr/sbin/cyrdeliver -m lists -a root ${local_part}"
return_output
log_output
prefix =
suffix =
user = cyrus
group = mail
home_directory = /tmp

now what happens: if imap server goes crazy also cyrdeliver segfaults!

Child process of local_delivery transport
(running command "/usr/sbin/cyrdeliver ${local_part}") was terminated by
signal 11 (Segmentation fault)

...now the problem is that all messages are bouncing! I'd prefer to have them
in the queue so I can bring the imap server back to life and don't loose any
mails...

I've looked into the manual and found something possible depending on the
result code - but the child *dies*. Any idea how to accomplish this?

We are using:

Exim version 3.35 #1 built 04-Mar-2002 23:05:40

Any hints?
--
Torsten