I can't create working policy.

I have some problem, every 10 seconds smtp traffic come to exchange interface. I create policy firewall "from wan to lan interfaces, source external range ip-addresses from traffic come, destination any interface, (I used ip range, subnet, single ip address), service ALL, action DENY", that policy set in the first place, and that policy don't work! I thought maybe the session was active, I manually stopped it in FortiView. Did not help. 

Create email filter profile. Enable "email address check", enable "block/allow list" enter ip address from Iran which traffic come, use that security profile on policy. Not work.

please help me!

why I can't upload more imagine?