[Exim] spamassassin only for specific domains: how?

hello,

i've successfully set up spamassasin with exiscan. (exim 4.3.2,
spamassassin 2.6.3) however, some of my clients prefer to receive their
mail unfiltered and want to deal with spam locally.

my idea to achieve this was to create a domainlist no_spamd_domains and
put an accept statement in front of the spamassasin test like so:

--snip--
data_check:

   accept       domains = +no_spamd_domains

   deny  message = This message scored $spam_score points.
         spam = nobody:true
         condition = ${if >{$spam_score_int}{63}{1}{0}}

accept
--snap--

however, when i have this in place, exim temporarily rejects *all*
incoming mail with the reason

"temporarily rejected after DATA: cannot test domains condition in DATA
ACL"

has anyone got an idea, how I could have spamassassin scan only mails
to specific domains? or even better yet: has anyone configured it so,
that each domain has its own ham/spam database?

here's hoping ;-)

thanks,

tom
--
Tom Lazar, http://tomster.org