Securing Exchange 2013 RPC over HTTP

Hello!

I'm currently running a Fortiweb VM appliance (FortiWeb-VM 5.37,build0478,150618). We currently have OWA, and activesync going through this product. We would like to block traffic for service RPC over HTTP. As we want to block Outlook Anywhere (purpose: Outlook client connectivity to email w/o being on domain).

I was wondering if this is possible, as I see some threads regarding this on Fortigate. Thanks!