Forti-Web Deployment for Email/OWA

Hello,

Please share the deploy procedure for the Forti-Web to protech the OWA/Webmail. However, We have Sophos Email Gateway

in-line between the Firewall and Mail Exchange. How I will deploy the new Forti-Web to protech the OWA. Please advise me.

And I'm new to the Fortiweb. Do I need to place before the Email gateway ?.