[exim] enforcing spamassassin in data-acl

Hi all,

up till now I ran spamassassin according to the usual examples to tag my
incoming messages. The resulting acl-statements in the data-acl look
like this:

  warn message = X-Spam-Flag: YES 
       condition = ${if <{$message_size}{250k}{1}{0}}
       spam = exim
  warn message = X-Spam-Report: $spam_report
       condition = ${if <{$message_size}{250k}{1}{0}}
       spam = exim:true

Not quite unusual, I guess. ;-)

However, when spamassassin is unavailable incoming messages pass
untagged, which is quite undesirable.
I consider changing my ACL to something like this:

  warn message = X-Spam-Flag: YES 
       condition = ${if <{$message_size}{250k}{1}{0}}
       spam = exim
  defer condition = ${if \  
                   and{{<{$message_size}{250k}} \  
                       { def:spam_score}}{1}{0}}
  warn message = X-Spam-Report: $spam_report
       condition = ${if <{$message_size}{250k}{1}{0}}
       spam = exim:true

This should cause a temporary defer if my spamassassin is unavailable.

Any comments? Do I miss something obvious?
Basically, I "just" have to gurantee every message is tagged accordingly
before delivered to the users inbox. So an alternative would to to
accept the message and have it scanned later, but I definitly don't like
setups where I have to pipe messages into spamc or something like that,
they cause way too many headaches.

--
CU,
Patrick.