Stop Incoming Email Except from External Spam Filter

This is related to the following thread.

Stop Incoming Email Except from External Spam Filter

But when I add the below code to my exim configuration, it blocks sending emails from outlook as well. How can I allow sending by outlook or webmail, but receive email only from my spam filter IPs?

accept hosts = :
deny
!hosts = @[] : net-iplsearch;/etc/trustedmailhosts
message = This server does not handle mail directly

 

Thanks Michael,

I tried this as well. But the same issue, outlook clients also gets blocked. How can I restrict remote emails to be accepted only from my external spam filter + all emails sent by mail clients? maybe I should check the sending email domain?