[Exim] equivalent of domains = in data ACL

I run all my mail through SpamAssassin using the following data ACL:

acl_check_data:
  warn message = X-Spam-Score: $spam_score
    spam = nobody:true
    [snip rest for brevity]

As a courtesy, I act as a secondary mail spool for a couple of domains.
Their mail gets caught up in the above SpamAssassin check, which is
undesirable. What I'd like to do is something like:

acl_check_data:
  warn message = X-Spam-Score: $spam_score
    domains = ! +relay_to_domains
    spam = nobody:true

However, according to the docs, domains = can only be used in a rcpt ACL.

I'm fairly new to the whole concept of ACLs, so there may be a much easier way
of accomplishing the above. All I want is for any mail addressed to a domain
that exists in +relay_to_domains to bypass the acl_check_data entirely or, at a
minimum, bypass the SA checks.

Any suggestions?

--kurt