[Exim] Apply custom filter only to incoming messages

I have the following custom global filter which rejects incoming emails with specific words or phrases into their subject. However that works both ways, meaning that also messages from senders in my server are being blocked if the filter conditions are true which was meant to filter out only the incoming messages. How can I make the filter condition to apply only in incoming messages and not to outgoing messages too ? if $header_subject: contains "offer" or $header_subject: contains "upgrade" or $header_subject: contains "Attention" then fail text "Rejected" seen finish endif