[Exim] fail instead of freeze when stat() fails on maildir?

Hello All,

I made the following transport for delivering into maildir mailboxes:
local_delivery:
driver = appendfile
directory = /var/spool/mailstore/$local_part@$domain
create_directory = no
delivery_date_add
maildir_format
envelope_to_add
return_path_add
group = mailstore
user = mailstore

I want the delivery to fail when the direcotory for the account does not
exists. When this happens, exim freezes message with "defer (2): No such
file or directory: stat() error for /var/spool/mailstore/blah@???:
No such file or directory". However I want to return an error message
instead back to the user. Is it possible to configure this?

--
Best Regards
Vladimir Ivaschenko
Red Hat Certified Linux Engineer (RHCE)
Francoudi & Stephanou Ltd