[Exim] acl_smtp_data - no access to variables needed

Using and SQL statment to filter the subject works fine. however I can't
seem to get the information needed

MYSQL_GET_USER = select user from local_domains where domain =
'${quote_mysql:$domain}' limit 1

acl_smtp_data:

deny message = Message not accepted due to client filtering
set acl_c9 = $h_subject
condition     = ${lookup mysql {select user from block where '$acl_c9' like
CONCAT('%',condition,'%') and type='subject' and user='$
{lookup mysql {MYSQL_GET_USER}}' limit 1}{yes}{no}}

warn log_message = rejected due to bad subject
accept

Now from the book I can see that the variables domain/local_part are not
avaliable in the smtp_data acl's but I need to be able to get the
domain/local user value to get the correct user from the table.

Is there a way to set a global variable from one acl to the other?

Without this information its not possible to set a per user filter on the
subject data.

Regards
darren