Spamassassin Help

[hci]

I have the below in my exim.conf to scan messages with Spamassassin. Problem is if the message was scanned by Spamassassin on anouther server or a Spammer just inserts fake Spamassassin headers in its not scanned.

Anyone know a way around this?


spamcheck_director:
driver = accept
condition = "${if and { \
{!match_ip {$sender_host_address}{/etc/virtual/pophosts}} \
{eq {$authenticated_id}{}} \
{!def:h_X-Spam-Flag:} \
{!eq {$received_protocol}{spam-scanned}} \
{!eq {$received_protocol}{local}} \
{<{$message_size}{200k}} \
{exists{/home/${lookup{$domain}lsearch{/etc/virtual/domainowners}{$value}}/.spamassassin/user_prefs}} \
{exists{/etc/virtual/${domain}/passwd}} \
{ \
or \
{ \
{!eq {}{${lookup{$local_part}lsearch{/etc/virtual/${domain}/passwd}}}} \
{eq {$local_part} {${lookup{$domain}lsearch{/etc/virtual/domainowners}}}} \
} \
} \
} {1}{0}}"
retry_use_local_part
transport = spamcheck
no_verify