Exim's main.log displays
"Warning: ACL "warn" statement skipped: condition test deferred"
and then
"temporarily rejected after DATA"
The panic.log has multiple entries for "spam acl condition: cannot
parse spamd output"
It's only messages from this particular domain (other mail is being
delivered fine), we've tried adding the domain to a 'white list' as a
temporary fix, but I'm not certain that we're putting it in the right
place (SpamAssassin's local.cf file). There were 2000+ entries in the
main.log yesterday for messages from this domain (obviously most were
retries).