[exim] help with spamassassin size limit check

I'm trying to limit the size of emails that Exim passes to SA to a

reasonable size.  I've looked through the mail archives and found
basically two proposed solutions:
Changing the spam= line to:
spam=${if <{$message_size}{50k}{'nobody:true'}{0}}
and
condition      = ${if <{$message_size}{50k}{1}{0}}

But, they don't work.  I'm running 4.44 on FreeBSD 5.3 with the latest
exiscan (4.44-28)
I change my ACL's as follows:
# Drop messages over database defined threshold
deny   message = This message scored $spam_score spam points.
       condition      = ${if <{$message_size}{50k}{1}{0}}
       condition = ${if >= {$spam_score_int}{${lookup mysql{select
spam_reject_threshold from domain where domain_name = '${acl_m
0}'}{$value}fail}}{1}{0}}
       spam=${if <{$message_size}{50k}{'nobody:true'}{0}}
       sender_domains = !+whitelist_from_domains
       logwrite = Message rejected as spam. $recipients $spam_score_int

# Flag messages over database defined threshold
warn  message = X-New-Subject: *SPAM* $h_Subject
      condition      = ${if <{$message_size}{50k}{1}{0}}
      condition = ${if >= {$spam_score_int}{${lookup mysql{select
spam_flag_threshold from domain where domain_name = '${acl_m0}'
}{$value}fail}}{1}{0}}
      sender_domains = !+whitelist_from_domains
      spam=${if <{$message_size}{50k}{'nobody:true'}{0}}
      logwrite = Message tagged as spam. $recipients $spam_score_int

After making this change and restarting exim, I send a 1MB file through,
and SA is sent to grind on it for a minute or two.

Any help would be greatly appreciated.

Jerry
http://www.syslog.org